Unitag

This module allows administrators an avenue to manage free tagging terms while still encouraging users to suggest new terms.

Examples of potential usage:

• If a tag added by a user is a synonym of an existing term, (optionally and) automagically replace it with the existing term. This can also be used to handle alternate spellings of a term, typographical errors and so on.
• If a tag added by a user uses the related terms feature of the taxonomy module, optionally tag the node with those terms as well.
• Optionally also insert the ancestors (parents, grandparents etc.) of the provided tags.
• Make a free-tagging vocabulary read-only. Non-existent terms are not included and are instead sent to a management interface where they can be dealt with appropriately.

The management interface mentioned above includes the following features:

• Save as new terms.
• Save as synonyms of provided root terms.
• Save as child terms of provided parent terms.
• Delete

Any new terms which are approved are also automatically associated with the nodes that suggested them in the first place.

Other modules that might be of interest include Suggested terms, Synonyms etc.