Here is a decidedly incomplete list of AudioUnits known to work with QLab 3. Please add what you learn!
For an AudioUnit to work with QLab 3, it must be 64 bit, be identified as an effect, and report a "tail time" (think reverb time).
IMPORTANT: Some AudioUnits only work with a specific number of channels, therefore some AUs will only work in certain situations. For example, Apple's AUMatrixReverb requires exactly two input channels, so it will not work on an output in 3.0 (because outputs are single channels), nor on a Mic cue (unless the total number of input channels for the device you're using is exactly two.) QLab 3.1 adds the ability to use stereo AUs on outputs.
- Blue Cat Audio (good flangers and chorus effects.)
- Klanghelm (nice "analogue" compressors, two of which are free.)
- Michael Norris Soundmagic Spectral (all kinds of weird spectral effects. As of Feb 25th, 2014, editing some effect parameters while audio is live may cause a crash. These plug ins are awesome, but not the most stable in the world.)
- Voxengo (in particular, they have a great free reverb.)
- Airwindows (a dual-mono reverb which works for mic cues.)
- PSP PianoVerb
- Waves (older than version 9.1)
- Altiverb (it technically works, but its initializing procedure is rather slow and happens every time a cue loads, so it effectively won't work.)