I've been googling this a little and searching the board but I couldn't quite find an *exact* answer. Is there a service out there where I can search by demographic? I know of quancast, compete, alexa, etc and the ability to look up the demographics of an individual site of course... But I assume since they have this data on each site, wouldn't it be logical that they'd have a "reverse lookup" for demographics? Say search all sites in a region that have a certain affinity (say 50% above average) to: "Female, 55-64, Some College"?
Is that what you get if you subscribe to Compete's Advanced offering, for example? Or does anybody have a package that suits what I'm looking for?
Or am I just craaaazy? 
Invent it >>>> bank hard.