I often think about doing exactly this. There is so much I want to learn:

- many awesome free online courses ( http://www.crypto-class.org , http://www.ai-class.com , http://www.ml-class.org , http://www.modelthinker-class.org , ... )

- dozens of non-fiction books sitting on my shelf I have yet to read (on computer science, programming, design, UX, software project management, system administration, computer security, business, time management...)

- thousands of articles and blog posts, bookmarked in my "to-read-later" folder

I've sometimes been asked if I'd want to go back to school to do a master that would complement my engineering diploma (e.g. MBA). But I think I could learn so much more by simply taking a year off and doing self-directed learning, using all these resources... Of course, I've set aside some learning time outside of work, but it feels like I'll never catch up.

Reminds me of this great article: http://www.npr.org/blogs/monkeysee/2011/04/21/135508305/the-...