On the automotive forums I get on it is a way to bring the discussion back to the top of the active threads.

I'm on SanAntonioGasPrices.com every day, and there "bumping" is used mostly by thread authors who just don't want to see their threads die for lack of participation. Chuck is just trying to keep this thing going, despite the fact that so few people actually contribute. As in any other endeavor, "just looking" doesn't add anything valuable for others.