What services with a bonus for a referred user do you know?

Question

Computer networks

I’ll outline right away: all actions take place to familiarize and test various systems with bonuses.
For the experiment, there are about 20 computers on Windows XP and Windows 7. We are interested in systems where any bonuses are awarded for a given user / friend who has installed any program.
A striking example is Yandex.Disk : for each friend you refer, 512 MB, limited to 10 GB.
As an option: Avast Antivirus : bring 7 friends and get a year of antivirus for free.
What systems and services provide bonuses for a referred user?
Not interested in financial pyramids.

Answer 1

Evernote gives you a month of premium for referring a friend.