Jeff Atwood at the Coding Horror blog links to a great introduction to Bayes' Theorem.
If indeed as has been claimed “Google uses Bayesian filtering the way Microsoft uses the if statement," we should all be well versed in the work of the mysterious Reverend Bayes…
I have been playing around intermittently with an interesting application of Bayesian classification for a couple of years. Perhaps this will inspire me to actually finish it up enough to put it up on the web.