Random Buzzers is run by Random House. It's a site geared to teens that, while it's basically a marketing device, is still a cool community for young bibliophiles. There's forums, groups, author interviews, book reviews - oh, and the best part is, you get points for participating in most activities and discussions and for writing reviews! What are these points for? Free books, of course! There's about 100 books available for purchase in the Random Buzzers store. All you need to buy a book is 15,000-20,000 points. Besides purchasing books with points, Buzzers can also win ARCs in weekly contests.
I've been a member of Random Buzzers for exactly a month. So far, I've gotten three books, though shipping seems to be slow (I haven't actually received these in the mail yet). Going Bovine and The Maze Runner were purchased with points, The Running Dream is an ARC.