http://www.jastaboelcke.de
Very good information on Jasta 2 and Boelcke
http://www.iwm.org.uk/online/index.htm
Imperial War Museum London
http://www.geocities.com/danlmurr/WWI_Planes.html
A fan of WW1, hasn't been updated in awhile but worthwhile
http://www.worldwar1.com
Trenches on the Web - Lots of content
http://www.theaerodrome.com/
World War I - Museum, Excellent site!!!