Agreed, the first Bleach opening was great. Very stylish and great music.
Cowboy Bebop's Tank! opening was always a favourite of mine.
Baccano's opening is like the spiritual successor to Cowboy Bebop's if you ask me, even though it's by a different artist, and equally as awesome.
Others that are fun to watch include Tenjou Tenge, Lucky Star, Melancholy of Suzumiya and others of the like with humourous dance / song / animations.