BakaBT
Formerly BoxTorrents, was hijacked by 2 administrators, but is still a good tracker for finding complete anime series.
Demonoid
Many popular old American TV and cartoon series! Anyone can dl the first few day’s torrents, but then you need to sweet talk a member into giving you an invitation if you want older torrents.
Gendou's Anime Music
Download tons of anime mp3s & now unlicensed anime episodes, as well.