The "Bob & Tom Radio Show" does not provide a comprehensive list of its comedians online, but signing up as a VIP on the website provides access to a library of past shows. Wikipedia and the iTunes store provide some information about past and future appearances as well.
The show's homepage displays a list of comedians appearing in the current week, as well as video excerpts from the most recent episodes. The iTunes store has an archive of excerpts from recent episodes, with the comedians listed. The show's Wikipedia page contains a list of recurring characters and the comedians who portray them.