This is probably the single most comprehensive sample set of the TR-909 you're likely to find, free or otherwise. Recorded with a Purple Biz Mk mic pre/DI in to a Mytek 8x192 A/D converter at 48kHz/24. Each sound was recorded with every control at five positions, resulting in a sample set that covers virtually every sound the TR-909 is capable of making. Have a look at the readme.txt file for a description of the naming method.

This is a collection of samples of the alphaSyntauri synthesizer, rolled in to Kontakt patches. Requires Kontakt 3 or later.

This is a small collection of patches for Native Instruments Massive synthesizer.

This is a complete Sampler-based Live Instrument Rack and Drum Rack containing every sound the Melo-Sonic 350 combo organ is capable of making. The instrument rack contains all six multi-sampled "voices," the monophonic bass synth octave, and macros for "Bass Boost" and "Vibrato" (their word; mine would be "tremolo.")

This is a complete sample set for Live Sampler from the Roland CMU-800R computer music peripheral for the Apple //e. It contains full-range multi-sampled Sampler instruments for the Bass and Melody voices (the "Chord" voices are identical to Melody, so they weren't included) and a Drum Rack with all the drum sounds.