I have compiled a list of all the free RTAS and AAX plug-ins I could think of. The list is nowhere near as long as a free VST list would be but nonetheless there are quite a few handy plug-ins here. Needless to say, while this is an RTAS and AAX plugin list, most of them should be available in VST and AU as well.
Audiffex – ampLion Free – Guitar amp simulator.
Avid – Structure Free – Free sampler.
Avid – Signal Tools – Metering.
Avid – Xpand! – Sample-based instrument with tons of presets.
Avid – D-Fi – Lo-fi and creative sound design.
Avid/Bomb Factory – Free Bomb Factory Plug-ins – Old Bomb Factory plug-ins gone freebie.
Avid/TL Labs – TL Utilities – Metering, metronome and tuning.
Avid/TL Labs – TL AutoPan – Panning effects.
Blue Cat Audio – Freeware Plugin Pack – A little of everything.
Blue Cat Audio – Chorus – Indeed, it’s a chorus.
Blue Cat Audio – Flanger – Indeed, it’s a flanger.
Blue Cat Audio – FreqAnalyst – Spectrum analyzer.
Blue Cat Audio – Gain Suite – Gain utilities for controlling volume.
Blue Cat Audio – Phaser – Indeed, it’s a phaser.
Blue Cat Audio – Triple EQ – A 3-band EQ.
Cableguys – Pancake – Panning modulation.
Dasample – Glaceverb – Emulation of vibrations and acoustic responses of different materials.
DDMF – Colour EQ – EQ with custom-made 4th order IIR filter.
Elysia – Niveau Filter – Nice filter.
HOFA-Plugins – ProjectTime – Measure the time spent on your project.
HOFA-Plugins – Meter, Fader & MS-Pan – Metering, fader and M/S decoder.
HOFA-Plugins – Goniometer and Korrelator – Gonio and correlation metering.
Human Touch Technology – SIKA Oriental Scale – SoundFont player dedicated to arabic and oriental scales.
IK Multimedia – AmpliTube Custom Shop – Amp and FX simulation.
IK Multimedia – T-Racks Custom Shop – Lots of stuff, and ways to buy more.
IK Multimedia – SampleTank Free – Sample-based virtual instrument.
Izotope – Vinyl – The tool for simulating vinyl.
JK Plugs – JK-Pipe – Captures default Mac audio input set in System Preferences.
Klanghelm – DC1A – Easy to use compressor.
Magix – Independence Free – Sampler workstation.
Massey – Massey Tools – Various handy tools.
Metric Halo – Thump – Bass monster.
Native Instruments – Kontakt Player – Sample player for use with Kontakt Powered instruments.
Native Instruments – Reaktor Player – Reaktor for players.
Native Instruments – Guitar Rig 4 Player – Modular effects processor.
Pleasurize Music Foundation – Dynamic Range Meter – Metering distributed by Brainworx.
Sonalksis – FreeG – And yes, even more metering.
Sonoma Wire Works – DrumCore Free – Drum plug-in.
SPL – FreeRanger – Slightly crippled equalizer.
Studio Devil – Studio Devil BVC – Amp modeling.
TriTone Digital – MuteTone – A workaround to the inability to shut off input monitoring.
Two Notes – Torpedo PI-Free – Speaker and mic’ing simulator.
U-he – Zebralette – Synthesizer.
UVI Sound Source – UVI Workstation – Sample player.
ValhallaDSP – ValhallaFreqEcho – Frequency shifter and echo.
Have I missed any? Let us know and I’ll add them to the list!