OnLine Money Making

A popular site that pays you for leaving it open (minimized) on your Desktop/Laptop 

or Smartphone is HONEYGAIN. 

Another site of this type is IPROYAL.

There is also EARNAPP.

Another one is Traffmonetizer.

And the last one Packetstream.

All of them are legal and can be used for earning passive income. They can co-exist in the same machine (PC - Laptop - Mobile - Tablet  - whatever...).