The M136 website is an excellent web resource with a significant amount of imagery generated by a number of photographers living in Germany throughout the cold war period. Whilst the cold war is extensively covered post cold war content is also good. The Web site is in German but its easy enough to navigate and most of the information is pictorial in nature
Exercises from 1960 through to 2010 are covered making this a first rate historical record. Most NATO nations are covered I have used it for US, Canadians, Danes, British, Dutch and Belgium
If the central front in the cold war or indeed the post cold war period is of interest to you this really is a brilliant web site.