I'd have to agree with others here that some OT posts are worth reading (e.g. algorithms; other languages), and some posts are probably from newbies that are having trouble finding the right forum to ask a question about a problem, and should be cut slack since they'll eventually contribute here.
It would be nice to have a user adjustable preference where I only see nodes above a certain vote level (i.e. > -10). The only reason I bother to even visit Slashdot is because I can surf at a high enough level to skip the bottom feeder posts. It has the benefit of dropping flamebait/troll replies as well (the unintersting ones at least :-). And if someone continually posts OT stuff, they will continually be voted out of sight.