I know the feeling :< Even though my mom's computer is mega-slow I'd still like to use it for certain things :(
I found out about Lunapic a long time ago, also through a friend of mine XD; Heck, I still use it for animating stuff since I'm still confused as to how PS's animating stuff works.
The RP looks cool <3 I'll consider joining it, though first I need to make a couple posts in a couple other RPs plus work on an application for one over at LiveJournal~
You could always do a Madoka-like one! :D Or at least keep to a "dark" magical girl plot or something like that.