[vidarh]

Almost every home-grown search function in existence could benefit from it, in my opinion. Everywhere where you have a useful feedback that imply good relevance (e.g. clickthroughs, customer actions), but do just straight textual keyword searches, a Bayesian approach can do better. Often there are more complex methods that can do even better, but the beauty of using a Bayesian approach is that it's so simple. I've seen so many cases where people spend tons of effort manually tuning product searches etc. when they can trivially have the engine automatically tune itself to what actually produces the best business outcomes.