My List: (which is rather small ... Just a list of what I've seen)
Amatsuki
Battle Programmer Shirase
Bleach (Quit viewing, also skipped all the fillers)
Busou Renkin
Chaos;Head
Clannad
Clannad: After Story (Currently on ep 6, enjoying it a lot)
Claymore
Death Note
Dragonball Z (Who hasn't?)
Elfen Lied
Fate/Stay Night
Gundam Wing
Melancholy of Haruhi Suzumiya
Naruto (Everything up until the fillers, dropped after the beginning of shippuden)
Nogizaka Haruka no Himitsu
Rosario + Vampire, both seasons
Rurouni Kenshin (also read the Jinchuu arc of the manga)
Samurai Champloo (18/24 episodes ... Should finish that some time)
Sayanora, Zetsubou Sensei
Shakugan no Shana I & II
Welcome to the N.H.K. (N.H.K. ni Youkoso)
Zero no Tsukaima (all seasons)
Also quite a few animes I watched but dropped after a few episodes (Higurashi, Ichigo 100%, Darker than Black)
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@Cxk: I have the first 3 volumes of the Yugioh series, it's pretty. Never knew they made an anime from season 0 though.

Also I found the Zabuza arc in the original Naruto a nice one as well.
@skelengel: Yeah Spirited Away is an anime movie.
@Meidou: Dude Mew Mew was awesome ... under the influence of certain illegal substances :3