This probably has been asked and answered before. I tried searching the forum but didn't see an answer right off.
I recgonize:
Arin - Pangya
Horny Girl - Kallen, Code Geass
Cat Girl - Various
Spunky Girl - Mikan, To Love Ru
I don't recognize the rest of them. The background of the Quiet Girl says Dragon Quest Sage. I suspect that the Twin-tail girl is from some game or the other. Sexy Girl pictures looks like they are all the same character but no idea where they are from.
On the MODS page there were some additional random characters:
Housewife - Kasumi, Ranma
MILF - Yuyuko, Touhou
Musician - Merlin Prismriver, Touhou
Noble - Aoi, Ai Yori Aoshi
Anyway, I haven't played video games much since my school days and help in identifying these characters more specifically would be appreciated.