Paul Graham is an extremely successful entrepreneur and all-around interesting guy. On his site he publishes essays he's written about business and entrepreneurship, and they're always lucid, informative and even fun to read. I especially recommend his articles "How to do what you love" and "What you'll wish you'd known". Great advice.
http://www.paulgraham.com/love.html
http://www.paulgraham.com/hs.html
http://www.paulgraham.com/articles.html