This question already has an answer here:
Would inferring tags from a question's title and body and filling them automatically into the tag field (or at least suggesting them separately as a hint list or something) be worthwhile?
Note that I'm not referring to the tag auto-complete that goes on already, mind you.
Edit: The way I see it, it's the people who struggle defining their problems who probably need the most help with getting them solved. That's what I'm implying with this question, just so you know.