Google AdSense. These pay-per-click ads appear on your blog. Every time somebody clicks on an ad (which is supposed to be about a subject related to your niche), you make a few cents. Small amounts each time, but it adds up. This is extremely hands-off. You just need to get a code from Google, place it on your website - and the ads will automatically appear on your blog. Google will only show ads that are relevant to your blog so it's a good experience for your visitors and maximizes the amount of clicks you get, meaning more income.
How to Get It: Begin with sites like UserTesting.com, YouEye.com and Userlytics.com. Register with multiple companies for opportunities to test as many websites as possible. Once you're in the system, you'll be emailed when testers are needed, and if you're one of the first to respond, expect to spend 15 to 20 minutes completing the test. Many sites require a microphone and/or webcam, which are built into most laptops—but if you need to buy one, they aren't expensive. The tester sites typically pay within a week or two via PayPal.
Donating plasma can actually work out better than selling your blood. It takes longer to donate plasma because they will put your red blood cells back in your system. The upside is that you can donate plasma as much as twice a week and you can make anywhere from $40-$60 per donation. You can make that $100 in less than a week if you can stomach the needle.