In terms of the site itself, I would want toi to be able to change your username. Some sites only allow toi to do it every 6 months after toi last changed it, so even if fanpop would just do that, I'd be a lot happier with the site. And if there was an app, that'd be awesome!
I would make the site a bit plus similar to Facebook, create an app, give it connecting to other websites, I would allow nom d’utilisateur changings too.
The only thing I'd like to really see on fanpop is plus trophée and plus opportunities for toi to get to talk with the admins of the site, like Dave and Cliff.