Since you're a Friend of Craftster you can view and add tags to threads. They're similar to a search in that all threads with a certain tag will pull up together but it's more accurate because people have to add tags themselves, not like the search where any thread with that word in it will come up.
If you see on the left, the lowest green button says "View Topics by Tag", that will take you to the "tag cloud" which is just a big cloud containing every tag on any thread.
If you look in the green bar at the top of a thread, the one that has the subject name and the number of views, right below it you'll see "Tags for this thread: Add new tag". If you click on "Add new tag" you'll get a pop-up screen in which to add the tags. There is an autocomplete that should help you with finding tags that already exist.
Here are the tips that show up in the pop-up window also:
These tags are public are meant to be useful for everyone!
When typing a tag, a drop down menu will appear beneath your entry giving you all possible matches to your entry. If you see the tag you want in the list, please select it.
Please use the singular form of words and phrases unless the word or phrase is typically plural (ie, glasses, pants, etc).
There's no need to enter super-obvious tags. For example, if a project is posted in the crochet board, it does not need to be tagged with the word crochet. The best tags to enter are those that indicate the unique theme or feature of this project.
Spaces in tags are allowed and they will be converted to underscores. No other puncuation is allowed. Example: Charlie's Angels would be entered as charlies angels and stored as charlies_angels.
Only swap galleries with very specific themes should be themes should be tagged. For instance, the Owl swap would be tagged "owl" but the Forest Friends swap would not be tagged. Swap discussions should not be tagged.
I'll try to get some screen shots at some point (although it may be a bit!). Let me know if you have more questions, though! I'm happy to help. I looovvvee tags.