Where can I find a list of the top advertising agencies - by city?

Is there a directory of advertising agencies by city? I found this site, http://www.americanadagencies.com/ but it’s a mess (for instance, under Portland it lists nothing – I know there are tons of agencies there). I’m looking for something a little more comprehensive. Also, if I simply google “advertising agencies in [city]” it brings up a lot of skeazy “Marketing Firms” that don’t actually do any good work. I’d like to see the top agencies in each city, big and small.

I have also checked the AAF and AAAA websites. Unless I missed something.

Thanks all.