FMA has one of the best stories I've ever had the pleasure of viewing. Gripping characters, nothing too cliche, I loved it (and of course, not complete unless you watch the movie afterward).
Cowboy Bebop is rockin', it'll make you view things a bit differently, that's for sure.
Love Hina's always a good choice if you're like me and a sap for romance.
One Piece is one of the best action animes I've seen in a good long while. Granted, like all long winded massive episode animes, a few episodes could've done without, but it's still rockin'.
Trigun's rockin', no matter what else you've seen. Great characters, great character development, and amazing ideas about the human decision on life and death.
Full Metal Panic is a good one, especially if you watch all three "seasons", The Second Raid and Fumofuu (good Lord I spelled that horribly wrong). One of the better mecha animes, and one of the more humorous ones.
Oh,
YouTube - DeathSponge NotePants part 1
^And this one.
