Your old college textbooks, gaming consoles and personal electronics gathering dust in the basement or attic may be worth a lot of money. Amazon.com has made it easy to find out if your items are worth anything through its Amazon Trade-in program. Hundreds of thousands of items are eligible; all you do is find your items and ship them to Amazon -- for free. It's as simple as a few clicks of the mouse. You'll get up to 80 percent of the original value of the item back in the form of an Amazon gift card.