Ghost in the Shell 2 (GitS): Innocence wasn't bad. Its a MAJOR head f**k though. Some trippy stuff going on. Its not quite up to the standard of the first though.
GitS has 2 series by the way, they're pretty well thought of but I've not got my grubby mits on them yet.
Now... the Appleseed remake is real nice. Even though the cell shading fade annoys the hell out of me, the story is great. And anyone who watched the original and was disappointed that the eight legged cannon didn't do much will absolutely love this remake. PLUS the great news is this is part of a trillogy, 2nd should hit mid-year and the 3rd in 2006.
Appleseed comics demand a great following in Japan... but then so do worn nickers.
If you like your hentai to have plots go with Urotsukidoji (4 films). These are really evil demonic films, and I swear to GOD I didn't know they were hentai till I saw the first.... then the second.
As mentioned, Gunsmith Cats is a great series with very pervy minded artists. Other great T&A series' would be Vandread and Burn Up.
Animenfo.com is a nice site for listing anime, and theres a forum too. The votes make me think that this site is prodominately voted on by americans, as Tenchi Muyo would never slip as far as 97 on a japanese poll.
Full Metal Alchemist listed as number 4 is a FRIGGING AWESOME series. Viewers of Trigun and Vandread will love this. Its the same mix of mostly serious script with a blend of irreverent humour. The serious has some very serious moments though. It truely kicks ass, and I've only seen the first 30 eps (out of 51).
Furi Kuri a.k.a FLCL is a small 6 ep series, and its comedy gold. They don't care about breaking the 4th wall at all, one scene cuts to them backstage with a little pic-in-pic of the action still going. Another rips into southpark.
From the top 200 on animenfo.com the ones I've seen and recommend are:
4 Fullmetal Alchemist
6 Berserk
9 Cowboy Bebop (watch before Knockin')
18 Cowboy Bebop - Knockin' on heaven's door
22 Neon Genesis Evangelion
29 Furi Kuri
30 Full Metal Panic!
36 Trigun
38 Vandread 2
45 Noir
62 Vandread (watch it before 2 though)
63 Initial D - First Stage (it aint bad if you like that sort of thing, animation is a tad odd though)
67 Hellsing
79 Ghost in the Shell
94 Akira
100 Evangelion: End of Evangelion
107 Macross Plus
154 Ninja Scroll
169 Bubblegum Crisis: Tokyo 2040
173 Lupin III: The Castle of Cagliostro (Lupin the 3rd is the charaters name, this isn't the 3rd film, but there are others)
Blue Submarine 6 doesn't make the list, which is a crying shame.
I personally liked Fist of the North Star film (animated version not the real actors one).
Gunsmith cats doesn't make it on either.... yet Card Captor gets in there twice.... damn stupid kids, shouldn't be allowed to vote. Least the frigging SPINNING TOPS one doesn't make it on. So horrible I've blanked the name from my brain.
(jebus... did I type all that?)