Many online retailers offer adjustments when the price of an item you’ve purchased drops within a certain amount of time. Paribus is a free service that takes advantage of this fact. Paribus monitors your purchases, watches for price adjustments or late deliveries, and requests refunds when applicable. Those refunds go back into your pocket. You have to allow the service to scan your email for receipts, but it works with a variety of big retailers, including Target, Nordstrom, Walmart and Costco.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.