Code Geass: Hangyaku no Lelouch - Half of the cast knows other half does not.

negima

[img]http://i415.photobucket.com/albums/pp235/carlQT_2008/Tsunayoshi_sig_by_Radic4L.png[/img]

Kizaru, the only person who can say Ben Beckman without his lips touching

just CARL is fine

Ultimate!! Hentai Kamen

One of the funniest manga I've read to date

[img]http://lh6.ggpht.com/Nabith/SH6-3kv9ZsI/AAAAAAAAAqQ/rAYBC9mbDcE/s400/darth_pika_avatar.png[/img]
FEAR THE FORCE LIGHTNING BROTHA

littlet bit different from the other proposals:
Detroit Metal City
Nicoichi

sandly with only 1 scan until now:
Switch Girl!!
Spray King

Crying Freeman's a good bet.

Nurarihyon no mago - The main characters is quarter yokai, human the day and the master of the nura clan (yokai) the night. His classmate is a fan of yokai so he made a club to investigates them and the mai character, Rikuo, is in that club... They always are in dangerous situations so Rikuo save them...

http://www.mangaupdates.com/series.html?category=Secret+Identity
try this?

zetman

Maybe Bloody Monday......
Here's one I'll just throw at you not sure if you'll like it Harlem Beat wa Yoake made