I made a topic like this a long time ago...
Anyway...
Kokoru no Chizu - One Piece (Probably my most favorite opening ever)
Brand New World - One Piece
Aaaaaaaaaand these, because I can.
http://www.youtube.com/ watch?v=8RnebJFjvrM
http://www.youtube.com/ watch?v=I5EIC0YYAX0
Because they're... questionable... >_>