ASUG.com allows you to "Tag" content to make it easier for people to find.
Whether you are adding a document or a Blog post (like this one) or discussion, there is a section at the bottom of the screen for "Tags."
Simply begin typing some relevant keywords and select from the pop-up the tag you want to use. If no one has used the word as a tag before, just type in the keywords that you think someone might use to search for the content you are adding.
Then users can filter content by these tags. See the link below for an example: