My seven year old daughter loves books and wanted to have a book party so...we made her invitations into "books"--title page was "An Invitation to My Party...by Kelly", and
then each page was the info for the party.
We decorated canvas book bags with glitter glue, made bookmarks, played book charades, had a book relay (keep a book balanced on your head), and then had a book scavenger hunt. I split them into teams and gave them each a stack of books--mostly chapter books for this age like Magic Treehouse--and then a list of things to find, like the name "Heidi", a book with no humans, a picture of a ferris wheel, etc. They really got into that and it took up a good 20 minutes (always a good thing when you are having an indoor party in Maine in March!) I splurged and ordered a book cake, but I saw some good recipes online. For favors they already had their bag and bookmark, plus we went to the library's book sale on "buck a bag" day and got a bunch of 7-year old appropriate books, which my daughter loved picking out for each kid and they loved getting!