piece of cake, I had one she is 13 now.
mp3 players are great gifts , if she does not have a computer you could down load her songs. there running pretty cheap now for a 1g as low as 14.00
also gift cards are big for kids.
It's been a while since my daughter was 11, seems to me she was really getting into video games at this time. If you have a Game Stop or similiar such video outlet near you, used games are $10-30 with new ones around $40-50 just check and see what/if she has (e.g. Sony/Wii/X-box and stationary or portable)
"We believed in our idea - a family park where parents and children could have fun- together."
I was all about gift certificates back in the day (you know when you got a certificate...), 11 was all about the gift certificates.
I had a weird idea that... one thing my mom did when I was little/that age was she got me makeup but (and a big but here) it was colors that were "idiot proof" and good quality. You could get her a Bare Escentuals kit, where she could sleep in it and be okay...