Here are a few interesting WW1 panes
Hotchkiss 47mm cannon in the nose of a French Tellier flying boat
http://www.geocities.com/CapeCanaveral/Hangar/8217/fgun/fgun-bi.html
Bristol M1 monoplane fighter
http://www.ctie.monash.edu.au/hargrave/bristol.html
Bias against monoplanes due to past wing breakages led to this plane being used for training only
Blackburn Kangaroo
Sank one U Boat and damaged several more
B.A.T. FK.23 Bantam
Fighter with the best performance of its time (post war), 1917
http://www.koolhoven.com/history/airplanes/bat/
http://images.airliners.net
Not WW1, but interesting
Vickers 161, 1931
Designed to carry upward firing cannon in cockpit
http://1000aircraftphotos.com/Contributions/Braas/4037.htm

Hotchkiss 47mm cannon in the nose of a French Tellier flying boat
http://www.geocities.com/CapeCanaveral/Hangar/8217/fgun/fgun-bi.html
Bristol M1 monoplane fighter
http://www.ctie.monash.edu.au/hargrave/bristol.html
Bias against monoplanes due to past wing breakages led to this plane being used for training only
Although the M.1C had a superior performance to many of the current RFC front line types, it was not used operationally over the Western Front.
Blackburn Kangaroo
Sank one U Boat and damaged several more

B.A.T. FK.23 Bantam
Fighter with the best performance of its time (post war), 1917
http://www.koolhoven.com/history/airplanes/bat/
http://images.airliners.net
Not WW1, but interesting
Vickers 161, 1931
Designed to carry upward firing cannon in cockpit
http://1000aircraftphotos.com/Contributions/Braas/4037.htm