What is refer-a-friend? Essentially, you make money for using a service and telling others how great it is. Most of the times, you’ll get a unique link that you can share with friends directly or throughout social media. Whenever anybody clicks your link and signs up and/or makes a purchase, you’ll get a bonus. The bonus can be in the form of cold hard cash or an account credit.
While we all have some extra time, it often doesn't feel like it. But it also doesn't take too much effort to make some extra dough on the side. We're not talking about millions upon millions here -- we're mostly talking about doing small, bite-sized projects to generate some fast cash. And depending on your skill set, you could easily make a few hundred dollars or even a few extra thousand per month. 
Tools & Resources: I’ve written a pretty comprehensive guide on the best web design software that covers both free and premium software packages. If you’re serious about becoming a web designer, then I recommend purchasing the full Adobe Creative Cloud Suite. At $49.99 per month, this is probably a bargain considering what you can achieve with this set of tools.
Getting businesses to advertise on your podcast, either at the beginning or end or both is a great way to create a revenue through podcasts. Most businesses won’t be keen to advertise on your podcast until you can prove a large number of listeners. Therefore, it is unlikely you will be able to start out from the get-go with sponsors. But once you accumulate regular listeners or a high number of downloads from iTunes, you can start to sell advertising space on your podcasts.
Keep in mind though, you don’t need a website to do sponsored content since you can also get paid if you have a lot of social media followers. My wife has a pretty big Instagram following, and she gets all kinds of sponsorships. Not only does she get paid in cash, but we get a lot of free stuff, too. We’ve received free rugs, free lights, and free carpet cleaners. She only promotes things she loves though, so this strategy works really well for her.

This has become a popular business model for online entrepreneurs over the past several years, and will probably just continue to grow in popularity. The best thing about selling online courses is that once you do the up-front work in creating the course and setting up your marketing strategy, you can get paid over and over again for work you do once.