What can you do with your idle internet when you are not using it? What can you do with your computing power?

This idea is to list everything you could possibly do with your idle internet/CPU, and then do something that is worthwile from that list. 

Mine cryptos, for self or for charity? work in scientific distributed computing?

I really don't know if someone can transfer actually some of his internet to someone else. There could be both technical and legal impediments.

One needs to take into account that you will expend more energy and need to replace the computer faster if you share CPU.