http://www.shareaza.com/
Open source and merges Gnutella, Gnutella2, & EDonkey networks!
It's awesome as hell.
...or
http://www.easynews.com
$10 a month for 10 gigs of downloading. Contains TONS of newsgroups. If you use their NNTP protocol, it'll cost ya 25% less in downloads.. so you download 10 gigs, it'll only count for 7.5.
There's also a utility you can run from grid.org that's very similar to SETI, easynews has a team on there. If you join their team, you get 1 free gig for every 15 days of CPU time. I put it on all my computers (8 total) and have a few VM ware clients running it, I get about 1 free gig per day.