RoughDraftAudio has released its own VST audio plugins, and had plugins released by others
[Note: Currently all plugins are Windows only]

RoughDraftAudio BetaBugs Others
A variety of released freeware VST plugins are available here.

There are also some beta plugins available from The Labs.
Between 2004 and 2009, BetaBugs released a well regarded collection of innovative VST plugins, all with graphics by Alex Volmer AKA Mully.

Duncan was responsible for:
FloFi Deluxe

He also wrote 'Vascillator', included on the Computer Music magazine cover disc, and 'Duckling Compressor' for the KVR Developer Challenge 2007.

RoughDraftAudio have also had software released by MIDI Madness and N-Track (the nVocal plugin),
and contributed to aspects of releases by EarMaster and GForce Software, amongst others.