Stagnation is death, at least of the human spirit. Education is an investment in your self-confidence, your perspective and your ability to navigate the world you live in.
Often I run into people–including myself–who do not know where to look for resources that will challenge them in their specific area of interest. This link has free resources for just about every niche. Enjoy.
Thank you to Marc and Angel Hack Life
Image credited to Flickriver: http://farm4.static.flickr.com/3070/2968868322_89504703d4.jpg