Extra Cash

I'm always looking for ways to bring in a little extra cash without having to dedicate a lot of time to the effort. One thing that works well for me right now is selling my books on Amazon.com. I love books and buy them fairly regularly. So when I finish a book I always look it up on Amazon to see what it's bringing used. If it's selling for a decent price I will add mine to the listing. I love their service because:
1 - It doesn't cost you to list you items. They just take a fee if the item sells.
2 - You don't have to write a listing. You just input the ISBN number in their search box, when the item comes up you click the box to sell yours and complete their form to create your listing.
3 - They collect the money and notify you when the item is sold. My account is setup to automatically transfer the earnings to my bank account every two weeks. You could also use your earnings to purchase items from Amazon.com.
4 - They tell you what the fees are if the item sells when you create your listing so there aren't any surprises down the road.

I don't make much money doing this. It's usually a few bucks a month, but it gets the books out of my house and makes me a little extra money without a lot of effort. For me, this is a win win situation.

Do you have any methods for making a little extra money?