my users have developed a system to 'rate' threads. generally speaking your average usefull thread (on my forums) will have 10 views/post. if it is particularly usefull it will have less then 10 views/post, and obviously if it has more then 10 vies/post it is deemed more a more useless thread. of course thats just a generalization, but maybe you could devide the # of views by 10 (or whatever), and then get the ratio of [views/10]osts to rate a thread.

of course thats just an idea, but i would require hella-less work then coding up a rating system.