What specifically is she too smart in? Is she advanced in her reading and writing skills? In which case, work on reading and writing with her. Lots of books and items to write with. Work books that are fun with writing areas in them. They make all kinds of games for kids as they are learning. Phonics games, math games, Scholastic has a lot. I also like teachers supply stores, they have an unending supply of fun educational things for kids to do.
To foster creativity, buy things for her to make collages out of. Music may interest her------ a kindermusik program or musicgarten (google for places in your area).
Make sure you pursue physical endeavors and social endeavors as well. good luck
Look for things designed for slightly older children. Puzzles, are great, but of course you need some variety. I would look around at the different toys, items that challenge little one's minds and get things for maybe a 5 or 6 year old. If she is very bright she will get bored easily, so you want things that may be a little difficult for her. Keep going up in age appropriate items until you feel she is being challenged enough.