On the topic of 303 clones, the program rack303 by David
Karla is just about the most fun I've ever had clothed.
It runs under BeOS, which means you can run 8 instances
of the program and tweak your frigging brains out.
It sounds perfect, syncs to MIDI (or the GeekPort if
you've got a BeBox -- I don't)and includes some extras
you can't get on a real 303, like 6 different waveforms,
delays, stereo panning, etc. And it's free.
The only catch is that it only runs on top of BeOS,
so unless you've got a fast PCI Powermac or a
BeBox you're SOL.
http://www.zog.net.au/dak/rack/index.html
303's are cuddly and all, but with the
advances in software synth modeling over last
12 months or so I'd save my money and buy
a nice computer instead.
-d.w.