What are some good adult animes?

You'll probably enjoy Chobits and DearS.

You mean Mature or Pervy anime?

What do you mean? Hentai, Ecchi, Mature? o.O

Hentai:
Sora Iro; Mizu Iro

Ecchi / Mature:
Popotan
Goshuushousama Ninomiya-kun
Boku wa Imouto ni Koi wo Suru
Kimi ga Nozomu Eien
Maburaho

Fist of the North Star (1984);
Ninja Scroll (1993);
Ghost in the Shell (1995);
Rurouni Kenshin (1996);
Perfect Blue (1997);
Cowboy Bebop (1998);
Hellsing (2001);
Basilisk (2005);
Blood+ (2005);
Death Note (2006).

Good Adult Animes

Exactly -
Be specific, then others may be able to help you.
Also good to give off a few genres.
Josei, Mature, Seinen, Ecchi, ADULT.

Like mature anime look for anything that has the name ninja scroll(even the makers of it), berserk(read the manga too I squee like a fangirl reading that), afro samurai, hellsing, and shigurai(sp)death frenzey. Hentai anime cool devises

Well it depends on what you have in mind when you say 'adult'. If you mean Hentai...Well, there's a LOT out there...

'Berserk' is an 'R' rated manga with a great plot. Unfortunately the anime version by comparison is quite disappointing. It's still interesting and worth checking out though.

Other suggestions I have:

Ninja Scroll, Wicked City, Urutsoji (I have no idea if I'm spelling this correctly...)

If you're looking for Hentai...Well, a quick google search will provide you with the most popular titles. I hear LA Blue Girl is very popular.

h20 footprints in the sand