Search for Warm Showers in the Marketplace on Windows Phone 7 or the Store on Windows Phone 8. Or click here.
Warm Showers for Windows 8 (the PC operating system) is coming soon.
Thanks to Randy for his patient and enthusiastic support. And to Robert and Steve for helping me test. And to Christopher Meyer (author of the iPhone app) for making his source available. It proved useful in initially cracking the web service calls.