Suggested terms - module which solves part of the same problem CMT tackles
Description
http://drupal.org/project/suggestedterms
This module provides "suggested terms" for free-tagging Taxonomy fields based on terms already submitted. It replaces the description field on free-tagging fields with a clickable list of previously entered terms. If javascript is not enabled the list will still appear but not be clickable. It provides the best of both worlds between a pre-existing list of terms and the ability to add new terms on the fly as needed.
Well, community-managed taxonomy will try to provide the true best of both worlds, but this solution is a lot lighter weight, and here now!

Module with some similar purpose to Community Managed Taxonomy:
http://drupal.org/project/unitag
"This module allows administrators an avenue to manage free tagging terms while still encouraging users to suggest new terms."