Ask HN: What are some good projects/resources to learn distributed systems?

I'm a kind of person who likes to hack on projects to learn things. If I am learning a new language, I'll think of a problem that I want to solve. After reading some syntax I'll start hacking on a solution.

I have decided to learn distributed systems.

I think this weekend would be a good start to hack on things. I can continue later in the week I understand I won't pickup distributed systems over a weekend.

What resources do you recommend for one trying to learn distributed systems on their own?