A list of fun stuff I can think of off the top of my head...
Gundam (Big franchise so you can go really right or really wrong)
Ranma 1/2
Dragonball (Classic franchise)
Escaflowne
Rurouni Kenshin (AKA: Samurai X)
Neon Genesis Evangelion
Code Geass
Death Note
Mado King Granzort
Sailor Moon (Shut up, you know you liked it...)
Trigun
Spriggan
Grave of the Fireflies
Ninja Scroll
Macross (Another big franchise)
Samurai 7
Samurai Champloo
Berserk
Detective Academy Q
Yakitate Japan
Cooking Master Boy
Saikano (AKA: Saishuu Heki Kanojo)
Bleach (Started out good, but started to get crappy a while ago...)
Naruto (Same as Bleach)
One Piece (Same as Bleach)
.Hack (Another franchise with multiple shows)
Full Metal Alchemist
Chrno Crusade
Hajime No Ippo
Initial D
Prince Of Tennis