As a companion to SamIam, please see the recently released book "Modeling and Reasoning with Bayesian Networks" by Professor Darwiche. Click here.
SamIam is a comprehensive tool for modeling and reasoning with Bayesian networks, developed in Java by the Automated Reasoning Group of Professor Adnan Darwiche at UCLA.

Samiam includes two main components: a graphical user interface and a reasoning engine. The graphical interface lets users develop Bayesian network models and save them in a variety of formats. The reasoning engine supports many tasks including: classical inference; parameter estimation; time-space tradeoffs; sensitivity analysis; and explanation-generation based on MAP and MPE.