Selling books to companies such as Moola4Books can net you a tidy sum of money, depending upon the books that you have to sell. College texts might get you more (but romance novels? Not so much!) At any rate, if you're raking your mind for ways to earn extra money, you might be interested in their promo. They're giving away a total of $50,000 ($5 bucks at a time) to customers who sell their used books to them. They have a handy ISBN entry form and you can get a quote for your books there. They do have a minimum - 5 books/$8 total - and they even pick up the shipping to them via USPS. Get PayPal for your books! Here's a snippet from the press release, that includes the promo code you need:
.... Moola 4 Books is giving away $5.00 free cash to the first 10,000 customers that use the coupon code "freemoola5." "$50,000.00 is a lot of money; I hope this campaign helps several people in need of some extra cash. This campaign also means a great deal to us; Moola4Books.com has always been a great service that serves a great need."