Since summer is coming up you should buy a children's plastic beach pail with a little shovel and then fill the bucket with some candy she likes (: and maybe sunglasses?
Depends on what kind of girl she is... A book, bath and body works, a movie, pre-ordered Halo 4, a Three Days Grace tee-shirt.
What is she into?
Maybe a gift set from Bath& Body Works, a gift card, a cute t-shirt maybe
a Starbucks coupon and a perfume?