This list is 99% shoujo sooooo:
Inu x Boku SS
Dengeki Daisy (Personal favorite)
Kamikaze Kaito Jeanne
Chobits
Full Moon wo Sagashite
Fruits Basket
Sailor Moon (It's a bit different than the anime)
I second The Ancient Magus Bride (They're making an anime for is and I'm so exceited)
Tonari no Kaibutsu-kun
Lovely Complex
Stuff I haven't read but looks good:
Akai Ito
Annarasumanara (Made by a korean manga artist)
Ao Haru Ride
Black Bird (It has some smut. I started reading it but never finished it.)
Bloody Kiss (Started but never finished)
Bokura Go Ita
Chrono Crusade
DearS
Gakuen Alice
Honey and Clover (I've only seen the anime)
Hot Gimmick
Kaichou wa Maid-sama
Karin (Chibi Vampire)
Kimi ni Todoke
Kobato
Nana
Orange
Paradise Kiss (I've only seen the anime)
Rooftop Princess
Spice and Wolf
Time Stranger Kyoko
