United States Weather Radar Data Feed or API?

NOAA has a SOAP API: http://www.nws.noaa.gov/forecasts/xml/

Several private APIs are listed here:

http://www.programmableweb.com/apis/directory/1?apicat=Weather

I was looking for radar data awhile back to overlay on a google map. This site offers it for free and they provide some sample code to get started for google maps and some other online maps:

IEM Open GIS Consortium

The map tiles they provide are not limited to radar and as far as I can tell they are all free to use.

Radarmatic has a JSON API at http://radarmatic.com/api.html

Update: link broken, project no longer active