Well, let's see...

If you look near the bottom of the page where you're reading this, you'll probably see:

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Tags
adding tags, fishy, hi there from lynn :), question, tag from darkrunner, tags
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All the entries in the real list are links but I only linked one in this copy. If you click on any item in that list you'll get a list of threads that have been tagged that way. For the last one, "tags", right now there are two, this thread and one other. I tagged them myself

If you go to Advanced Search (there's also a link at the top right of every forums page) you'll see, among the search options, one for "Search by Tag". Enter "tags" (or whatever tag you're looking for) in that box, click the "Search Now" button, and you'll get a list of all threads with that particular tag.

Right now tags are being used on only a few threads so searching by tag may not bring up much. If we tagged more threads, that feature would eventually become more useful.

By the way, the word "tags" as used in this thread refers to search tags, which are entirely different from BB code tags.