Keyword association

To aid in search, allow keywords to be associated with questions.
This is similar to the existing tagging functionality, but as tagging is restricted to a defined set of terms perhaps a new attribute with looser validation is required?

Example of keywords aiding in question discovery:


Hrmmm, I wonder if this could be built into the search engine. Like a database of Synonyms/Related terms so when the user does a search we can provide more accurate results. Have you seen something like this done before @tim?