I'm getting an iPad Friday, and one of the major uses for me is being able to read PDFs. Currently I'm scanning all of my school papers for an index into my computer, organized first by subject, then unit, and each unit is it's own PDF. Is there any good app for the iPad that can not only read the PDFs I make but also have a way of organizing them into folders or something along those lines? If not then would it be feasible to organize each subject into a photo album? Thanks.