Google Earth - Worldwide vertical aerial photography system that has to be downloaded. Contains still photos submitted by the public.
Geograph British Isles Project - The Geograph British Isles project aims to collect geographically representative photographs and information for every square kilometre of Great Britain and Ireland.
Bing Maps - Worldwide vertical aerial photography with Ordanance Survey mapping and Oblique Views of UK
Google Maps - Worldwide vertical aerial photography.
SKYSCAN - Since 1984 Skyscan has built up an photolibrary of over 250,000 aerial photographs captured from masts, balloons and aircraft. New photographs can be commissioned to order, a searching service is also offered to locate and supply old aerial photos of the UK.
