Just go hunting in the depths of the various sub-forums, if you are so inclined. I agree with Cammy. Not a good idea for the Top 10 active topics. Would have to be a side box and even then, there are some forum topics I'd rather not see dredged to the surface. Random or not.
For your own amusement, go nuts. Put whatever weird keyword(s) in the search box and see what you get. Just don't be bumping them to the top, please.