While writing also falls under the category of an actual work at home job, it can be great for extra cash, too. Particularly content sites. These are sites that post writing assignments for any of their approved writers to grab, and for most you only need average writing skill to become an approved writer. While the pay isn't fantastic, if you can write fast, you can for sure earn substantial extra money. Most of these sites will pay a penny per word or more:
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.