So far I've used:
Napster (of course)
iMesh - fast speeds, no probems at all. My favorite by a long shot.
Winmx - I don't have luck here, seems no matter what I am trying to get, I sit queued for eternity.
Morpheous - SLOW, with lost downloads
Blubster - simple to use, but it seems the other people must cut me off for some reason, even tho I'm sharing ??
Edonkey - good for programs (as napho said it would be)
Audiogalaxy - not the real one tho, I have the one that piggy backs from audiogalaxy. Havent used it yet
Audiognome - I think I still have it, tho I havent used it in eons
I think I have more, but I'll have to check when I'm at home
