What sort of classification are you trying to do? Text, I assume. If it's text and you need something open source, or just a pointer to how to write one yourself, you could read the article I wrote for Dr Dobbs on this subject: http://www.ddj.com/development-tools/184406064
There are quite a lot of toolkits out there that do Bayesian things (take a look at libbow or Weka).
I'm looking for something that is open source that I can start using right away with minimal configuration... I'm not smart enough to create my own, but clever enough to take somebody else's work and cater it to what I'm trying to do.
There are quite a lot of toolkits out there that do Bayesian things (take a look at libbow or Weka).