Just wanted to share two resources I found useful while searching for thesaurus development and management resources. These definitely have been recurring requests in the SIG IA world.

American Society of Indexers Thesaurus Software
http://www.asindexing.org/site/thessoft.shtml

Willpower Information: Software for Building and Editing Thesauri
http://www.willpower.demon.co.uk/thessoft.htm