Why not pop into her bedroom when she is not around and have a look at what books are lying around now to give you an idea as to what interests her.
Some good books I used to read include the Molly Moon series (firs one is Molly Moon and the Book of Hypnotism) by Georgia Byng. Clarice Bean are also good books, by Lauren Child. If she is a more mature reader, then you could perhaps get her started on some Jacqueline Wilson, but don't be too hasty because some stuff in those books could be pretty full-on for a 7 year old. Also, the older Roald Dahl books like Henry Sugar are good. You could also get her a journal or notebook as people that like to read are often also good at writing.
BTW check if she owns any of these books before hand. Sneak into her room while she's out.
Peppa Pig is all the rage I understand - although it might be too young for her - that's what I am buying my niece - albeit if the Ozzie Post doesn't steal it. It is a good sign when her brother tries to take it
(and the Australian Post Office).
If they are arguing over toys I think that is a good sign you got it right.
Jacqueline Wilson is good.
Its my sisters birthday on Wednesday. She loves to read and i want to get her a book of some sought. Shes only 7. I never know what authors she in to, as she never reads to myself or outloud. Shes very quiet and very raley speaks 2 any1- not even about her books. Im hoping i can get some suggestions on good books/authors for a seven year old girl. (plz not princess's- she dosent like them)