If your technically competant, use IRC. Me careful though, you don't want to get hacked and get a bot on your computer
Also a familiar one not mentioned yet is bittorrent, used to be better but is still pretty good. IRC is by far the safest in terms of law suits though because it's not considered "maintstream" enough for the **AA to target yet, and also generally you don't get fakes and you get stuff sooner. Most things on kazaa etc are filtered down from IRC.