Short: Presearch rewards users in cryptocurrency for using their search engine, 
Decentr rewards users for using their browser.
This won't make you rich, but it's possible to make a few extra bucks.

Introduction video about Presearch

Introduction video about Decentr

First register an account on Presearch: https://presearch.com/signup?rid=2888817
You will get 25 token bonus for using my invitation link!

Then register an account on Decentr and download their browser: https://referral.decentr.net/?referralCode=cwJ-AwRz
You will get 1000 uPDV bonus for using my invitation link!

That's it! Use the browser as any other normal browser and earn passive income.