Will Lindsay has introduced his YM_MINI, a hardware USB synth based on the YM2149:

The chip is most well known for its use in the Apple II Mockingbird soundcards and Atari ST computers. The YM or the chip from which it was derived (GI’s AY-3-8910) also created the music and audio in the Intellivision, Vectrex, some MSX systems, Sinclair ZX and Spectrum home computers, and many arcade machines.

The synth can be played via a live controller like monome or Oxygen8, or any midi-capable software such as Logic-Pro, Energy-XT, FL_Studio, Reaktor, Reaper, Max/MSP, PureData, Protrekkr, ztracker, — pretty much anything that can sequence midi!

The synth has 3 channels or square waves, a stereo noise channel, and a bizarre envelope generator for strange volume envelope effects. I’ve programmed it to work entirely via midi channels 1,2,3 & 10 (for noise), with the envelope and registers controlled via midi CCs. It has pitch-bend, and velocity control and uses a look-up table for fast pitch accuracy. So far tested to work on OS X and Windows with several software and hardware setups.

Lindsay is selling both YM_MINI kits and assembled synths, for $15 & $85, respectively.