Do you have any 'fun' yet productive things you do when you are done for the day?

This could be learning, advancing skills, or even mundane work that you enjoy.

Personally, after writing for hours and hours, I enjoy practicing drawing. I'm hoping that this will be useful in the future when I sketch out design solutions as an engineer. So far, already came in handy at my 9-5.

That's something I consider 10% productive, 90% fun. Still better than wasting time on reality TV. I put starcraft at 5% productive, 95% fun, with the 5% giving me insane mouse/keyboard skills that have baffled coworkers.

Do you have anything like this?