Check out:

Many universities have produced Bayesian network software. B nets are used in the software of giant companies like Google, Microsoft, IBM, Oracle, Autonomy (now part of HP), SAP, SAS, ... But how about smaller companies? This is a list of smaller companies that make a living almost exclusively from selling B net software and services

  1. Agena Risk
  2. Apara (dVelox)
  3. Bayesia (BayesiaLab)
  4. Bayesian Intelligence
  5. BayesServer
  6. Causal Links
  7. Charles River Analytics
  8. Hugin (HuginExpert)
  9. IDI
  10. Lumina (Analytica)
  11. Norsys (Netica)
  12. IET
  13. SMART Research

Other companies that I've heard mentioned but no longer seem to be active, or at least don't have an easy to find website, are:

(last updated, Jan, 2015)