Advanced Tags & Prefixes 3.2.2a

Some of its features:

Define all prefixes manually through the Prefix Manager--even for open-tag systems.
Show common tags and prefixes across your site with the Tag Cloud Widget.
Add, fix, merge, and remove tags and prefixes in bulk through the Tag Manager.
Choose a prefix when posting any prefix-enabled content, separate from tags.
Control where and how tags and prefixes are displayed.
Add custom HTML formatting to your prefixes, allowing colors, images, and much more.
Limit prefixes by member group and location.
Require a prefix in certain forums*.
Add tags and prefixes to topics in bulk with Saved Actions or the Mass-Add tool.
Apply a prefix to topics imported from RSS.
Set a default prefix and tags for all new topics in a forum*.
Override the global tag settings by forum*. This lets you enter custom tags in some forums and not others, or change how many tags are required, or have a prefix option without any tags at all.
Display topic prefixes in the page title, last post info, and as filters under each forum's description, if you want.
These added settings should work for all tag-enabled content types. The focus of this application is Forums and topics, but it also supports Calendar events and any other tag-enabled content. That being said, I cannot guarantee compatibility with or support all possible applications and circumstances.