Want to buy a blu-ray movie, but not interested in paying full price? Search on CamelCamelCamel for what you want then subscribe to the associated “3rd party used price” RSS feed (look for the RSS icon: 
). You’ll get an RSS update each time the price changes.
They do look good on your bookshelf, but are you really ever going to read them again? You can free up space in your home, save the environment, and spread knowledge throughout the world by getting that book off your shelf into the hands of an eager reader. One of the easiest ways is through Amazon: do a search for your book, click on the ’sell yours here’ button, and you’re on your way. If you are feeling philanthropic you can sell your book for as little as $0.01 plus shipping. Or charge what it’s really worth and you’ll earn some dough for something new to read. Works great for old games too.