CryptoTab is a free download that you install into Chrome. It claims to mine cryptocurrency in the background while you are working.
There is also a referral program where anyone you refer and installs the plugin, he can use the service and will generate a portion of their coin traffic to you for referring them. (Invite your friends, family and associates).
It have some setting about the mining power you want to use (off-low-normal-high).
The concept looks nice but there is only one way to see if this app is working.
Here is my referral link so that you can start and try this app:
https://getcryptotab.com/114396
Good Luck!