Three sources are all you really need:
BitTorrent is my usual fare, though if I can't seem to find what I'm looking for I'll head onto IRC, and if I'm still not finding it I head to Emule... which takes forever, even if it does have everything I've ever looked for.
Every now and again I try that Japanese program, Share, again. Although I never return a good search result with it despite using obvious cluster words. And getting node IP addresses is just annoying.
Proud member of BUMS.
Yeah, back again. Sort of.