"fun"is pretty subjective here. What do you do for a living? I ask because I've been in the same boat, and most of my learning has come from work interactions. I try to make the time to automate everything I can, even if it's something that shouldn't be automated or is effectively a waste of time, I'm still learning so it's not entirely a waste.
One of the projects I started at home was web servers, automating the creation and configuration of simple lamp servers on my desktop at home. You can do it work virtualbox, VMware, hyper-v, or a number of other free vm software, and you can pick any distro you'd like to run the servers on, with or without gui. I never finished working this one out since the dish with all my vm's died, but I did have a lot of fun muddling through it with PowerShell, python, and php.