BAYESIA: Bayesian Networks and Data Mining Tools
Home of theBMS Bayesia Market Simulator, BE (Bayesia Engines) and BGLE (Bayesia Graph Layout Engine) software programs.
http://www.bayesia.com/

Bayesian Network Repository
The Bayesian Network Repository is a place to share domains, tasks specification and task evaluation.
http://www.cs.huji.ac.il/labs/compbio/Repository/

Bayesian Network tools in Java (BNJ) - Kansas Stat
An open source software for probabilistic representation, learning, reasoning in Bayes nets and other graphical models. Developped by the Kansas State KDD Lab.
http://bnj.sourceforge.net/

JavaBayes, a Java library for bayesian networks
The JavaBayes system is a set of tools for the creation and manipulation of Bayesian networks. The system is composed of a graphical editor, a core inference engine and a set of parsers.
http://www.cs.cmu.edu/~javabayes/Home/