hi and welcome here aymoo
gnutella..has a few clients like bareshre and limewire..ect shareaza seems to be a popular one
fastrack..is the p2p network you use when you log in with kazalite..imesh(theres a brand new lite version about some where)..grokster... are some others that use this one..
ed2k network is another network again...emule recommended for this edonkey2000 has spyware
bit torrent ..some good info here on that -->
http://www.slyck.com/bt.php
theres a heap more follow some of the links there^