L> Mindfuck/something dark

You're gonna have to drudge up some okay ones. I've probably seen most of the ones that are gonna come to mind first. (But run them by me to double-check) Dig deep.

Visual novel of chaos;head is hot. Higurashi no naku koro ni is sweet too but you've probably seen that.

Mnemosyne
Ga-Rei -Zero-

I don't watch many dark series :<.

Stopped in the middle of chaos;head while it was airing, can't remember why. Might look into the visual novel (I'm a visual novel virgin )

Seen the other 3.

[COLOR="RoyalBlue"]Baccano!
Mind Game
Kaiba

If you really want something dark and mysterious, in the same sort of manner as Higurashi no Naku Koro Ni, then look up Umineko no Naku Koro Ni, a visual novel by the same person who created the former. Basically horror and suspense, and tons of mindfuck "wat" moments.[/COLOR]

Those all sound solid. =o
Gracias.