Paul Graham
Paul Graham is a lisp hacker who wrote several books about Common Lisp, became rich and famous by making what became Yahoo!Store, and is now developing a new lisp dialect, Arc.

His article A Plan for Spam is probably responsible for the current fashion of Bayesian spam filters. The full text of his book On Lisp is available; this is a really good book showing how use Lisps unique features (esp. Macros) to do cool stuff, although it is not for the faint of heart.

See his site: