Baltimore?
Not just in Baltimore, but also at least in Reno, NV. And the Clearwire WiMax isn't quite WiMax: (http://www.infoworld.com/article/08/09/29/40TC-wimax-road-test_1.html) "To be completely accurate, the Clearwire service is not officially WiMax but OFDM [Orthogonal frequency division multiplexing], the underlying technology behind the WiMax standard. Clearwire deployed the Reno network before the WiMax standard was final, but it is practically the same technology."
It seems to be fairly decent as far as coverage and speeds go, too, with download speeds between 1.5Mbps and 2.0Mbps, and upload speeds between 275Kbps and 325Kbps, on average.