http://www.amazon.com/Snowball-Warren-Buffett-Business-Life/...
This is by far the best biography on the man. Alice Schroeder did an amazing job. His life story is incredibly instructive whether you're an entrepreneur or an investor. When you study Buffett's life you get a deep appreciation for the intangible qualities that define extraordinary entrepreneurs.
Best business book I've ever read, and probably will ever read. I don't say that lightly. My copy is thoroughly dog-eared, highlighted, and I turn to it over and over again.
Will teach you far more business than any MBA will -- but only if you're serious about learning, and reading through 832 pages.
Read the statement of facts in the PDF as well: (http://sec.gov/litigation/complaints/2008/comp20810.pdf). After reading it, chances seem slim that he's innocent.