You just described my 8-year-old daughter!! She and my younger sons each has and loves their:
- Razor scooter ($30-$45 online at Walmart.com and in different colors)
- Nintendo DSi ($100+ depending on the color, or a DSLite is less) - if she already has a DS, you could get more game cartridges or a gift card to GameStop so she can pick out her own games
- Build-A-Bear animals (if it's about her, then I agree with the first person's recommendation about BAB - either take her there or give her a gift card - but if it's about me, I agree with the other posters since we don't need any more stuffed animals around here!).
My daughter also shares with her brothers:
- Bop-It ($15 online at Walmart - don't worry about the more expensive variations, just get the basic Bop-It, which will keep them busy for hours)
- two Zoom-O Disc Launchers ($10 each at Target, but 2-3 times the cost elsewhere). You can play one by yourself, but get at least two so that she has the option of playing "catch" when there's a second person around. My kids play with these things constantly, both outside and in the house. Who knew it could be such a huge hit?!! Now we give them as birthday party gifts.
For her upcoming 9th birthday, my daughter wants a Nook Color (I got her a refurbished one online from Barnes & Noble), more Diary of a Wimpy Kid books (her favorite series), a pet rat (uh, no!), and a visit to BAB (I'd rather get the pet rat, lol!). She's on a travel soccer team, so I'm ordering some optional uniform accessories/spirit-wear items from the team's uniform vendor, and, after a ton of research on goals (price, size, quality), I ordered a folding portable 8'x6' soccer goal for our yard from Hayneedle.com ($55 and free shipping).
What about a class (or gift certificate for a class) through her local park district? My daughter is currently in a pottery/ceramics class that she loves, and she has previously taken a drawing class and a magic class that she loved as well.
You can't go wrong with a gift card to Learning Express, if there is a store location near her. Kids LOVE that place, and they personalize things certain items free there too.
My daughter also loves going to trampoline places. Perhaps take her there or give her a gift certificate. Xtreme Trampolines has 10-punch cards for $70 that can be shared with others, so she can use it on herself or invite friends.
Hopefully this gives you a range of ideas with different price points. Good luck!