What if there was a way to label topics into some sort of folder-like system? I think the hacker news community would be happy to self enforce a categorization

What if there was a way to label topics into some sort of folder-like system? I think the hacker news community would be happy to self enforce a categorization so when we go through one of these cycles, all related threads would show under one trending topic thread. I'm not sure how this could be programmed in. But it's an idea. If a thread on the home page has a keyword like Google or Facebook or Apple or iPad then there should be a high penalty for other threads with the same keywords.