StorJ is the best altcoin I have encountered in the term of usage. It is a coin that is spent on buy users wanting to store files, and that is where you come in. You can now hire out unused space of your harddisk, that Pi that is hosting your homepage or just from your homemedia centre. You can also cheaply rent space if you need some.
We all have unused space on our devices that are running 24/7, now make that earn you a little money on the side.
Personally, I have earned about 16 dollars with StorJ.
How to install and usage is located here.