Give Fairy Tail a quick read, its great fun. Is it a must-read? No, but if you enjoyed One-Piece, you'd probably dig Fairy Tail too. The art is similar to One Piece though, so that might give you hangups when you start getting characters confused (hey its 4 in the morning here). Other manga I've been reading... Ga-rei (hasn't been updated in awhle), Mx0, HxH, One Piece, ID, bleach.... basically mindless but enjoyable shounen mangas.