If you have an extra room in your house, consider listing it on Airbnb. Airbnb is a new way to travel for many people around the world. Instead of booking through expensive hotels, why not stay at someone's house? As a guest, you can choose high end to low end, choose to stay with other people or opt for privacy. As a host, it's a great way to make side money, utilize unused space, and meet new people! How much you can earn depends on your area so I recommend finding out by becoming an Airbnb host yourself!
If you live near a university, there are likely all sorts of research studies looking for participants. While I was an undergrad at Virginia Tech, I got paid $500 to participate in a 6-week dietary study. The study provided all my meals and paid me, but I had to eat a 5,000 calorie diet of 50% fat for 6 weeks, plus I had multiple muscle biopsies, urine/blood testing, etc.
Considering that you have a finite amount of time, passive income should make up a large part of your work. And if you're serious about generating any semblance of income online, then passive income should be one of your sole goals and ambitions. Why? Simply this. Wouldn't you prefer to do the work one time and get paid repeatedly as opposed to relying on your time to generate that income?
Robert said he did an average of 4-6 of these gigs per year for a while depending on his schedule and the work involved. The best part is, he charged a flat rate that usually worked out to around $100 per hour. And remember, this was pay he was earning to advise people on the best ways to use social media tools like Facebook and Pinterest to grow their brands.