Following this article of Lifehacker I decided to give a try to Crashplan, an online "cloud" backup service that seemed very promising to me because it supports many platforms (Linux and Android included) and offers an unlimited space plan for one computer for only $36 a year.
Installing the client for Linux is very easy, and presents all the typical backup options (timing, include/exclude paths, and so on).
I decided to include all the directory I already backup with a script of mine on a USB external hard drive.
The problem here is visible in the screenshot I saved: the estimated time for completing the first backup was 52 days!
It's not Crashplan fault, of course, but the fact is that here in Italy we are still very far from using a remote service like that.
Maybe I'll retry again in a a few… years.