Bayesian Network Repository - Maintained by Gal Elidan - over a dozen publicly available networks with documentation, in several popular interchange formats
Belief Revision - Software, publications, teaching material, and news on belief revision - from the Business and Technology Research Laboratory at the University of Newcastle, Australia
Decision Systems Lab (DSL) - Research group at the University of Pittsburgh with links to books and software on probabilistic, decision-theoretic, and econometric graphical models
Learning Bayesian Networks from Data - Slides and additional notes from a tutorial by Nir Friedman and Daphne Koller on automated learning of belief networks, given at the Neural Information Processing Systems (NIPS-2001) conference