I buy a half dozen books, read two or three, and then buy a half dozen more.
I probably only have six or eight (purchased) unread ebooks right now, but I've ordered books only about three times in the few months I've had my device. If I keep this up, I'll have a whole stack of unread books in no time!
I do plan to read them all, but my purchases tend to be in genres and as my moods change, I want different books.
Hopefully soon I'll have samples of every style that I like to read and I won't have to place orders every time I feel like reading a different type of book.