Thanks for the support, y'all!
I'm still amazed as to how people can get so many hits, though...
My bills aren't loudly marked, I guess you could say, though I consider them noticeable. I usually print the website on the bill as clearly as I can along with a saying like "Track This Bill!". If it's a 1986 bill, I write it either in the margin (on the back) or at the side going vertically (on the front). If it's a 2001 bill, I go for the undetailed area near the bottom center on either the front or back (bloody new bills! They barely leave any writing room!).
And no, I've never seen one of your WW bills. To be honest, I've never seen any marked bills before. But seeing as I'm in Waterloo a lot I try to mark any money I send in hopes that a bigger city will get better results!