The obvious answer is Junketsu no Maria. One of the best anime of all time.

And if you're feeling fancy, try Madoka or Yuuki Yuuna wa Yuusha.

You should also watch the two ova episodes for Gargantia, if you haven't already.

Senran Kagura (13)

Pokemon Origins (4)

Akame ga Kill. One of the best anime I've ever seen.

For some reason the entire internet and their mothers hate it with passion, so you may not want to take my word for it (though the pilot alone will be enough to help you decide if it's worth your time). I just thought it was all sorts of amazing (apart from the stupid fan-service stuff).

(Does anyone know if the plural of anime is "animes" or "anime". I see people spell it both ways all the time)

I'm not too big into anime, but you should watch Oban Star Racers. It's around 24 episodes I believe, and it's pretty awesome.

Black Bullet
The Sacred Blacksmith
akame ga Kill

I started watching a few animes lately and almost everytime I watched the last episode it turned out that it's not finished and that there is not going to be a second season (at least it's very unlikely). Dissapointing, as I really liked a lot of them.

So if you like incomplete animes (who doesn't? lol)
I can only recommend BTOOOM! (has some very mature elements and no I'm not talking about Ecchi stuff).
Also Deadman Wonderland is really fun (as in gory).
Same goes for Tokko.
Highschool of the Dead hasn't gotten a second season either so far, so it qualifies as being incomplete.

Other than that (complete animes):
Elfen Lied
Hellsing
Although those are quite popular ones you've probably already watched.

Thanks! :)

Kiba
Amagi Brilliant Park
Hataraku Maou-sama!
Tiger and Bunny
Death Parade

Akame ga Kill, Black Bullet, Another, Elfen Lied