I think it could be a good idea to exclude sites per Crawler (or Query) set.
For exemple, I would like Agent to search microsoft.com but not in a specific Crawler set (or query set) that is set up to search for Macintosh stuff in some starting sites.
That comes in handy when Follow link option is set to more than 1 depth. Basically I want to follow links but not if they end up in microsoft.com. And I want this behavior specifically for one specific crawler set. Not always…