Following are a few sites you can install once and earn rewards passively. It takes a couple minutes to get set up and going, but definitely worth the time for the amount they pay.
Kryptex is a passive income generator based on the computing power of your device. It is reasonable if you have affordable energy costs. It would be ideal for a solar powered home or a plan to make one if you can get a loan from someone, or some place on a line of credit to install solar panels on your house and then upgrade your computing devices. It is simple from start to finish, but really doesn't reward to high without the specific high end equipment needed to sustain a lifestyle. Works well if you're in your own home, and have around 20 thousand dollars for solar panels and a high end processing computer required for the mining. You can join and try it out to see if it works for you, if your electricity is included in your rent, or if you already have a decent computer. Other than these requirements for future growth, expect to earn a few bucks per month.
So far all I know about this site is you install it as an extension on your personal computer. You then earn points as some of your data is monitored. You accumulate points which can then be redeemed for Gift cards from a variety of stores including Best Buy, Amazon, and Red Cross to name a few. It looks to take around a month to reach the minimum 2000 point redeem mark equivalent to $10. It has a maximum of 10 referred users to the site, JOIN NOW FREE!!!
Works well if you have unlimited data on your phone or unlimited internet on your home network. It gathers internet usage statistics and pays you directly to your bank account. It pays low, still every little bit counts, and the more it's reinvested over time will add a significant amount of compounded income for the long-term. There is no referral program I'm aware of yet.