National Agriculture Imagery Program
Through the National Agriculture Imagery Program (NAIP), the US Department of Agriculture's Farm Service Agency acquires 1-meter aerial imagery covering the United States. The "leaf on" imagery is collected during agriculture growing seasons. It is frequently newer than other easily-available imagery (Yahoo, Bing) and can therefore be used for mapping recent changes.
In some areas (at least parts of Texas) Bing serves NAIP imagery.
For the JOSM WMS Plugin, the possible WMS url are
http://isse.cr.usgs.gov/ArcGIS/services/Combined/SDDS_Imagery/MapServer/WMSServer?request=getmap&version=1.1.1&format=image/png&srs=EPSG:4326&layers=0&styles=default& http://isse.cr.usgs.gov/ArcGIS/services/Combined/USGS_EDC_Ortho_NAIP/MapServer/WMSServer?request=getmap&version=1.1.1&format=image/png&srs=EPSG:4326&layers=0&styles=default& http://isse.cr.usgs.gov/ArcGIS/services/Combined/USGS_EDC_Ortho_NAIP/MapServer/WMSServer?request=GetMap&version=1.1.0&format=image/jpeg&service=WMS&layers=0&STYLES=default&
2010 imagery was added in May 2011.
A JOSM-format URL:
As of May 2011, final 2010 imagery is available and is also accessible via:
This is not always the latest imagery (example: the official NAIP server and MapQuest show more progress than Telascience on the US 54 expressway at Osage Beach, Missouri).
The USDA's Geospatial Data Gateway makes available downloadable county-wide image mosaics of NAIP imagery, other DOQs, DRGs, etc. Unfortunately, they are distributed in proprietary formats (MrSID, JPEG2000) and will require involved conversion before use in most software.