is there a genre you'd like? comedy? action? harem? super natural? Hentai? drama? romance? etc...

i'll give some action types first.

Samurai X, AKA, Rurouni Kenshin.
Black Lagoon
Bubblegum Crisis Tokyo 2032, 2040, crash,
Claymore
Cowboy bepop
Trigun
Darker than Black
Gate Keepers
Hellsing Ultimate
The Garden of Sinners, AKA, Kara no Kyoukai
Jin-Roh: The Wolf Brigade (movie)
Kurozuka
Robotech, AKA, Super dimension Fortress Macross
(and anything macross, the latest one though is Macross Frontier, if the SDF Macross is too long)
Samurai Champloo
Shakugan no Shana
Spriggan (movie)
Strait Jacket
Sword of the Stranger (movie)

other stuff:

if you're also into games, they're a few that are linked. e.g.
Valkyria Chronicles, Tales of the Abyss, Tales of Phantasia,

Aim for the Top (AKA. Gunbuster.) : old, but not bad
Aim for the Top 2 (AKA Die Buster) : much newer.
Aria the Animation (and its follow ons): if you prefere a very calm anime about nothing except daily life happiness. and gondolas.
mushishi
She, The Ultimate Weapon (this is sad...)
Utawarerumono