DOQQ

A Digital Orthophoto Quarter Quadrangle (DOQQ) is a digital raster image of an aerial photo mapped by the USGS. In a DOQQ, image displacement caused by terrain relief and camera tilt has been removed. This is a DOQQ of a portion of Washington D.C.

http://seamless.usgs.gov/website/seamless/products/1doqq.asp