Speaking of selling stuff online, that's another mostly passive way to generate income. You could generate an income stream for a while by clearing out your basement or attic and selling items on eBay or elsewhere. This can be especially effective with collections. If you have lots of games or jigsaw puzzles that are taking up space and not being used, they can be great sources of income. You might reap a lot by selling new and used clothing you don't need.
The sheer traffic that the android and iOS appstores host every day means that if you are able to make an app that is useful, there is probably a market out there for it. If you are able to make a hit, then the sky is the limit. Flappy bird is a great example of the success that one person can have in their spare time. The creator is generating $50,000 per day from ad revenue on his free game. 
Network marketers have long understood the power of these human networks, both the strong networks as well as the weaker networked relationships. People on the Internet develop networks of relationships, too. They collect email addresses and favorite website URLs. Affiliate programs exploit such networks, as do permission email lists. Learn to place your message into existing communications between people, and you rapidly multiply its dispersion.
Unlike having to either create something or store a physical inventory of something, selling digital products requires no overhead and no active work to earn money. The blog Paper & Oats put together a great guide on how to get started selling on Etsy. In this guide, they share a few ideas on digital products you can put together and sell in your Etsy store. If you’re someone who’s creative and knows how to design great-looking digital files, this might be a perfect option for you.
A truly viral product emerged from targeting a truly viral problem in the digital age, known as attention deficit disorder. Allowing people globally to channel their nervousness into an entertaining handheld device has allowed for the viral spread of Fidget Spinners. The products modest beginnings spread virally through school children and later through to adults. We started seeing fidget spinners in social media, memes with fidget spinners, fidget spinners distracting people while crossing the street, and of course, fidget spinners in the impulse purchase section of your local supermarket. This little product achieved a viral marketing status through providing a ‘solution’ to a viral problem and bringing about a world full of fidgetty temptation.