For anyone with an hour to kill in sorting through which of these links, accumulated over the past decade or so, might still be active and still have available the free-of-charge virtual instruments, audio-processing plugins, Kontakt and other sample libraries, and sound-effects audio files, hit them below. I myself tend to favor Mac-formatted AU and VST instruments and effects, but almost all of these should include (if still active) the PC-format VSTi plug-ins.
Bedroom Producers Blog - Freeware For Musicians!
Free music samples: download loops, hits and multis | 47,182 free sample downloads | MusicRadar
Free Mastering Software For Windows & Mac!
boscomac - instruments & fx Reaktor
Free Acoustic Drum Samples! - Bedroom Producers Blog
Download free samples, loops, vst plug-ins, patches, sound banks and more
SMDrums for RS5K and Kontakt (Free Drums) - Cockos Confederated Forums
GM Midi Instruments for Kontakt | bigcat Instruments
Converse Rubber Tracks Sample Library
KVR: All Plug-ins / Hosts / Apps On One Page
SM Drums | Deeply Sampled Free Drums for the masses
CINEMATIQUE INSTRUMENTS - Free Stuff
Center for Arts & Technologies at Seoul National University
Download « Etcetera Pipe Organs
Sonus Paradisi Forcalquier, France - Major European Schools - Organs
Hauptwerk Virtual Pipe Organ :: Hauptwerk Virtual Pipe Organ
CATSNU - Google Play의 Android 앱
Lightworks: The professional editor for everyone
Download | Juvul Audio/Visual Performance Tools
Steinway Grand 3 FREE! - Sampleism: snacks for your samplers
Audio Damage // Free Downloads
Super Secret Sample Page — XKORE
Kosmology/Multiverse – FreeFall | Homegrown Sounds
bigcat Free Instrument Lists: Totally Free Instrument by Type
Farm Animal Sounds | Orange Free Sounds
Mihai Sorohan Music Corner: free samples
BeatSkillz | Tools for The Modern Producer
MELLOTRON Premier - Free Mellotron Sounds Library
bigcat Maize VSTis | bigcat Instruments
Fine Cut Bodies | Sound Design
Alter/Ego :: real-time singing synthesizer - PLOGUE | Music Software | Developers
Starting Out With $0 AKA The Freeware Directory | AudioSEX - Professional Audio Forum
The Total Composure Orchestra V 1.0 : Xtant Audio : Free Download & Streaming : Internet Archive
Vortex SoundWaves v2 | SampleScience
soundethers space evolutions kontakt ambient cinematic library
DrumTROOP VST/AU - HOT Drum Machine Workstation For Modern, Urban, And Traditional Music Production.
U530 | Mercuriall Audio Software
ButtonBass Make Music online. Play the Virtual Piano With Your Keyboard.
31 Free Kontakt Instruments | SampleScience
Free goodies - Rossignol-Studio
Convert WAV ( or MP3, OGG, AAC, WMA) to MIDI | Bear File Converter - Online & Free
Sound Effects, Royalty Free Music, Sound Effect, Music Loops, Sound FX
HitFilm 3 Express - Free video software - HitFilm.com
Free Apple Loops for Garageband - Macloops
[FREE DOWNLOAD] - The #GameAudioGDC Bundle Part 2: 16GB+ of High-Quality #GameAudio
The #GameAudioGDC Bundle Part 2 - Tracklist - Google Sheets
Synister | The Synthesizer made for you
Tokyo Dawn Labs - Audio Plugins | Tokyo Dawn Records
Kairatune | Futucraft – Audio Software and iPad Music Apps for Electronic Music Production
Free Reverb VST/AU Plugins! | Bedroom Producers Blog
Free Sound Effects | Airborne Sound
Free Sound Effects (24-bit WAV) | 99Sounds
99Sounds | Free Sound Effects & Sample Libraries
MODWHEEL, Virtual Instruments and Sample Libraries | FREE STUFF
Free loops and samples | Free wav samples to download | Free sample packs
Free Teufelsberg NSA listening tower impulse responses
Kontakt Freebies Master List - AudioSEX.pro
Alan ViSTa - Free VST Instruments and Audio Units
Most popular / top free audio plugins (VST, AU) used on splice | Splice
100+ Awesome FREE Online Resources For Music Producers!
Rain Sounds Sound Pack | Orange Free Sounds
Game Boy Drum Kit - Kontakt & SFZ (Free Sample Pack)
Free VST Plugins! - Bedroom Producers Blog
A Collection Of Free Kontakt Instruments By Hideaway Studio! - Bedroom Producers Blog
Samplicity's Bricasti M7 Impulse Response Library v1.1 - Samplicity
Downloads : Tracktion 4 Free - Tracktion
Free Reaktor Ensemble: FM Radio
sforzando :: Free SFZ Player - PLOGUE | Music Software | Developers
sfz Format Resources - PatchArena
Product: TASCAM Hi-Res Editor | TASCAM
FREE SYNTH SAMPLES - EXS24 - KONTAKT - REASON - LIVE
Free SFZ Player - VST Plugin/Audio Unit, SFZ Format, Samples
Solo Viola Lite | Northern Scoring Tools
Roland RE201 Space Echo | Reaktor User Library : Entry | Community
Glitchmachines.com | Forward Thinking Audio Software and Sound Effects
Recommended Freeware Plugins « Zynewave
Kontakt Freebies Master List | AudioSEX - Professional Audio Forum
Anarchy Rhythms / Anarchy Effects
Royal Standart | Cmusic Production
Free Plugins - Stagecraft Software
FREE STUFF - Video & Filmmaker magazineVideo & Filmmaker magazine
News: VST plugins,music software,sound samples,loops, Dec 2014
u-he Intros Free ‘Experimental Reverb’, Protoverb » Synthtopia
Best Free Software for Making Music | AudioSEX - Professional Audio Forum
Software » page 5 » Free Downloads - DownTR
Free Stuff | Audio Imperia - EPIC SOUNDS FOR EPIC COMPOSERS
Phazor » Adam Szabo | Official Website
Free Pro Tools Plug-ins — Pro Tools Expert
AudioWeather Free - LeSound by AudioGaming
chokehold.net | Sean Pandy Drums
Free Weather Sound Effects: Rain, Thunder and Wind
KVR: LiveProfessor by audiostrom - Plug-in Chainer / Rack for Windows and Mac OS X
The free software sampler – Independence free
Daz 3D, 3D Models, 3D Animation, 3D Software
Free Stuff | Mercuriall Audio Software
Karoryfer Collection | bigcat Instruments
UVI Workstation - Free Player Instrument
PAREE KATTI MUSIC: Experimental Drums
Free Rhodes Samples | Free Sampler Instrument
Mihai Sorohan Music Corner: samples
IK Multimedia | SampleTank 3 Custom Shop
Vortex SoundWaves v3 | SampleScience
Shortnoise - Free 6GB Electronic Sample Library
Free music samples: download loops, hits and multis | MusicRadar
Download - blender.org - Home of the Blender project - Free and Open 3D Creation Software
freeSFX.co.uk - Download Free Sound Effects
Music for games, film and advertising
ANWIDA Soft DX Reverb Light - The ultimate free reverb plug-in for PC and Mac
Free VST Plugins, Free AAX and AU Plugin Download | Voxengo
Free Virtual Instrument Soundfonts
Ø:1 NI Kontakt Files | Professional Kontakt Files
1044 premium sound effects for you - for free! | A Sound Effect
12 Days of Christmas - Sonokinetic - Sample libraries and Virtual Instruments
T5 DAW | Free digital audio workstation - Tracktion
KONTAKT LIBRARY - Studio Major7th
bigcat Instruments: VSCO2 Rompler
Mixxx 2.0 User Manual — Mixxx User Manual
A1StereoControl - A1AUDIO - VST, AU, AAX & RTAS Plugins for MAC & PC by ALEX HILTON
A Free Background Vocals Sample Library - SoundBetter Singers
SoundBridge - A Free Full-Featured DAW Designed for Network & Mobility
Sample Libraries | Downloads | Waves
:: Plektron :: VST plugin :: DOWNLOADS
PaulXStretch plugin | Xenakios's Blog
SampleScience Player | SampleScience
Free Samples | CAPSUN ProAudio
VCV Rack - Open-source virtual modular synthesizer
SELTSAM | Entry | Reaktor User Library
TALKBOXKICKER | Entry | Reaktor User Library
REICHIAN | Entry | Reaktor User Library
BRUTE | Entry | Reaktor User Library
Crystal Goblets Eugene | Ableton Live Pack & Kontakt Instrument
Obxd Synthesizer – Emulation of famous OB-X, OB-Xa and OB-8 synths
bigcat Instruments: GM Midi Instruments for Kontakt
Palette - Primary Colors - Red Room Audio
Christian's private site - EQs & Filters - Christian's private site
LABS - Free Virtual Instruments
Free VST Plugins, Free AAX and AU Plugin Download | Voxengo
Gater: Free Stereo Trance Gate
SocaLabs – VST / AU Audio Plugins
Pianobook Sample Library — pianobook
Expanse - Texture Generator – Puremagnetik
Stone Voices • Application «Sound Art»
Computer Music Magazine | MusicRadar
Reverb Drum Machines | The Complete Collection
LIBRARIES | The Alpine Project
WarmPlace.ru. Virtual ANS Spectral Synthesizer
0on3 - Older Release's UPDATED (vol. 1) | AudioSEX - Professional Audio Forum
MELLOW | Acoustic Double Bass | Virtual Bassist by ujam
Sound effects library - Free sound effects | Adobe Audition
The Free Orchestra - ProjectSAM
Cello Choir & Pad - 2 FREE Kontakt Libraries - Pyjama Planet
Podolski: Nice and easy | u-he
Audio Plugins for VST/AU | Physical Modeling and Virtual Analog Synths and Effects | NUSofting
Sinnah VA synth freeware| NUSofting
The 10 best freeware synths you need to download right now
45 VST Plugins, AAX and AU Plugin Download | Voxengo
Pluginboutique - renaud.sarti@psoteo.net | plugin015
Resonator Glockenspiel - FREE - decent|SAMPLES
VCV Rack - The Eurorack Simulator
Download Bigcat All Kontakt Libraries Bundle [oddsox] Torrent - Kickass Torrents
Download BigCat Piano Collection Version 2 KONTAKT [oddsox] Torrent - Kickass Torrents
Free Audio Samples From NASA - AudioSEX.pro
NASA Audio Collection : Free Movies : Download & Streaming : Internet Archive
Free Kontakt Instruments Archives - Logic Pro Expert
Free DDLY Dynamic Delay - Better UI - Free Video Tutorials - Logic Pro Expert
Bedroom Producers Blog - Freeware For Musicians!
BlueLab | Audio Plugins - VST, VST3, AAX, AU - Windows and Mac OS X
AAS Swatches free Sound Pack Series compilation
VCV Rack Archives | Patchstorage
ADSR Sample Manager by ADSR - Find the perfect sound in an instant! for Mac/Windows - ADSR Sounds
Tokyo Dawn Labs – Discontinued Products | Tokyo Dawn Records
Free Kontakt Instruments – Sonixinema
Free Lofi Vocal Telephone Effect - TeleVox | Viator DSP on Patreon
Red Rock Sound | Audio plug-ins for music applications
Analog Obsession is creating VST, VST3, AU (WIN / OSX) | Patreon
Analog Obsession is creating VST, VST3, AU (WIN / OSX) | Patreon
Novation Software | Novation Downloads
Focusrite | Focusrite Downloads
Focusrite Plug-Ins | Focusrite Downloads
Saffire (Legacy) | Focusrite Downloads
CINEMATIQUE INSTRUMENTS - Mociula Lab | Modular Electronics
CINEMATIQUE INSTRUMENTS - Free Instruments Overview
Codec | Modern Degradation VST3 / AU Plugin | Lese
Free audio plugins | Wavesfactory
Free Kontakt libraries | Wavesfactory
Sixth Sample | Straightforward Audio Plugins
DSP56300 Emulation Blog | Emulating the Access Virus C & other virtual analogue synthesizers
HZ Multiplier free VST plugin by Higher Hz
DLYM - Delay Modulator for Desktop and Mobile - Downloads | Imaginando
discoDSP - OB-Xd - OBERHEIM INSPIRED VIRTUAL ANALOG SYNTHESIZER - AAX / VST / VST / AU / IOS
MONSTER Guitar, a FREE VST Guitar for Making a MIDI-Mockup for Your Song - AgusHardiman.TV
MONSTER Bass, A Complete Bass Plugin For Your Low-End Needs - AgusHardiman.TV
MONSTER Ethnica, The Best Free Plugin of World Instruments - AgusHardiman.TV
KXStudio : Applications : Carla
SoundBridge - A Free Full-Featured DAW Designed with Simplicity in Mind
The Ultimate Beat Maker – Serato Studio
Waveform Free | digital audio workstation band editing software - Tracktion
Soundbridge - My Account - renaud.sarti@poste.net/soundbridge015
Free Sounds and Music Samples - Royalty-free sounds from Serato Studio
BPB Dirty LA - Bedroom Producers Blog
Soundiron Rainsong - Free Nature Recordings & Ambient Pads for Kontakt
SampleScience - paywhatyouwant
Free Stuff - Electronik Sound Lab
Audio Damage Free And Legacy Products
SnareBuzz | Snare rattle simulator | Free audio plugin
GOYO Voice Separator | De-noise, De-Reverb, De-Voice - All in One Plugin
Free & Paid Virtual Instrument Plugins (VST, VST3, AU)
Transpanner - 3D audio panning
DOTEC-AUDIO（ドーテック・オーディオ） - "DeeDoubler" VST2 & VST3 & AU & AAX plug-in
CRASH! BARK! BOOM! The USC Sound Effects Library | Internet Archive Blogs
Zrythm - Digital Audio Workstation
Free music composition and notation software | MuseScore
Old Audacity versions download
The Free Orchestra 2 » ProjectSAM