I assume this is just for the main AAR stream, and not those of affiliates and third-party relayers.
http://www.kurthanson.com/archive/news/092905/index.aspWebcast Metrics August '05
(M-Su 6a-12M)
1 Net Radio Sales (Ad sales network)
2 Digitally Imported
3 AccuRadio
4 RadioIO(Multiple formats)
5 Club977(80s hits)
6 Air America Radio(Political talk)
7 Big R Radio(Multiple formats)
8 GotRadio(Multiple formats)
9 Wolf FM(Hits radio)
10 Beethoven.com(Classical)
11 Energyradio.fm(Multiple formats)
Webcast Metrics August '05
(M-F 6a-8p)
1 Net Radio Sales(Ad sales network)
2 Digitally Imported (Electronic/Dance)
3 AccuRadio (Multiple formats)
4 RadioIO (Multiple formats)
5 Club977 (80s hits)
6 Air America Radio (Political talk)
7 Big R Radio (Multiple formats)
8 Wolf FM (Hits radio)
9 GotRadio (Multiple formats)
10 Beethoven.com (Classical)
11 BoomerRadio (Multiple formats)
As for terrestrial radio, Radio and Records publishes 12+ overall numbers on it's site (though advertisers buy based on demographic ratings breakdowns). 12+ at least gives a vague idea of how they're doing. For a list of affiliates, go to AAR's site and look up the markets. Or you can find a list of AAR and non-AAR stations on my blog (click banner below). I'll do a little digging as well too and get back to this thread.