Great idea. I think 5 random submissions should get a front page chance. It increases variety and as the other person said, it also combats group-think. Five out of thirty, even in the worst case scenario (not even one of them is interesting to a person) is not enough to degrade HN.

Also something has to be done about the fact that many news stories that are bad PR for certain companies or good about their competitors are quickly dispatched to page 2 and 3.