Yep you get one credit for each person that signs up and posts their first 10 books. Be sure to go on the discussion forums and check out the Book Bazaar. People offer great deals on there 3 books for 1 credit, 4 for 1...etc.  They also sell their extra credits on there, so if you are short of credits, you can get them cheaper than buying directly from paperback swap.   I've already sent 3 orders of books out and received 2 orders of books.  I'm loving it......