If there's an animé you'd like to suggest then by all means post the name in the comments.
Already Seen-
Soul Eater
Trigun
Hellsing (OVA/Ultimate)
Full Metal Alchemist
Outlaw Star
Detroit Metal City
Death Note
Soul Eater
Afro Samurai
Bleach
Ghost in the Shell
Cowboy Bebop
The Melancholy of Haruhi Suzumiya
My Little Pony Friendship is Magic
Metalocalypse
The Big O
Dragon Ball/Z/GT
Tenchi
Already Watched-
Love Hina -
Black Lagoon -
Now and Then, Here and There -
Blood+ -
Eden of the East -
FLCL -
The Last Exile -
Desert Punk -
Blue Gender -
Highschool of the Dead -
Wolf's Rain -
Claymore -
Air Gear -
Currently Watching- Beck
To Be Watched-
Gurren Lagann -
Serial Experiments Lain -
Mind Game -
Umineko no Naku Koro ni -
Cat Soup -
Boogiepop Phantom -
Paranoia Agent -
Jigoku Shoujo -
ChaosHead -
Blue Literature Series -
Ergo Proxy -
Mnemosyne -
Baccano! -
Ayakashi: Japanese Classic Horror -
Elfen Lied - 0%
Pet Shop of Horrors -
Colorful -
Requiem From the Darkness -
le Portrait de la Petite Cossette -
Full Metal Alchemist: Brotherhood -
Shiki -
Elfen Lied -
Higurashi no Naku Koro ni -
Hugurashi no Naku Koro ni Kai -
ef - A tale of memories -
ef - A tale of melodies -
Kara no Kyoukai (all seven of them) -
Shiki -
Deadman Wonderland -
...Got some more suggestions of the Dark and Twisted.
Lunar Legend.
If you want something dark and twisted try Kuroshitsuji and D.Grey Man.