So far I'm very impressed with this script. It just works.
I'm having one issue with it though. I find it's pulling in a lot of irrelevant topics. How does it search for forum posts? I'm getting stuff just completely unrelated - in a couple of my categories it's like 70% irrelevant. I've wittled down my keyword lists (i noticed the forums with the most accurate content had the smallest keyword lists), but it's still pretty noticeable.
Can you explain the search algorithm a little, or should i just limit each category to just a few keywords?