I really like the customized results feature. It allows me to just remove sites that I don't like, push up ones I do, etc. But to keep track of why I changed a setting for any particular domain, I'd have to use a seperate note or something.
Given that you can add litterally a thousand domains to that list, might it be an idea to allow us to add a note to them? Just for personal reference.
The "Personalized Results" page would have an extra column called "note" or something similar.