I was searching for a tag (knitting) and got some results, which were good results, but I would like to be able to point the searchbot to a specific site (knitty.com) and let it know that this is a site about knitting. Am I just slow and this is already possible, or is it something that might become available in the future?
No you're not slow. At the moment you can't submit specific websites as all the results are gathered from websites like Google, Yahoo, digg and del.icio.us to keep the quality high and prevent spam. If it's at the top of the list somewhere like Yahoo then it will appear in Searchbots.
That said we are looking into a way of allowing you to suggest websites to your Searchbot once you've trained it to a certain level and your decision making has been validated by other Searchbots.