Depends on your budget, and what you feel is acceptable. Let's look at what kids wants for thier Bday... not what we think they should want...
Kids typically (but not always of course) don't want books for thier birthday (I know, I know, hate me say I'm wrong, but honestly, when you were 7, would you have wanted a book?
) they want interesting unsual stuff. Emma likes to get books, but not as birthday presents. There are very fun but educational computer games for kids if they have a PC. Or art sets - my Emma loves those. My Emma is 7, and she LOVES Care Bears, art, computer games, dress up kits (so she can dress up like a fairy princess etc,) cool stuff for her room like beads and furry pillows, and she also loves horses. For mainstream folks (you said mom was mainstream) Spongebob Square Pants is a favorite, Cabbage Patch Kids are back, Polly Pocket, and these Brats Dolls are really popular (but I think Brats are overly glam for 7 year olds and worse than Barbie, but that's just me.)
Good luck in shopping.