Lulu/Shirley FTW
Milly/Rivalz
Euphie/Suzaku (I'm a sucker for this one)
Viletta/Orange-kun
Cornelia/Guilford (in that order :D)
Raksharta/Cecile
CC/Mao
CC/Lulu

I'm a slight Lulu/Suzu fan (if it's fluffy I'll fall for it) but not entirely. I don't see the yaoi love like others do.

Wait... wait screw this, Geass is one giant orgy. Yaoi, yuri, incest, beastiality and mecha love. It's got everything a fan wants!