WW1

Canvas Eagles - WWI Dogfight Ruleset compiled by Eric Hotz. "Sweep the skies free of the dreaded Fokker scourge! Lead the Flying Circus in a Jabo over the Allied trenches!! "

Flying Circus - WW1 rules on the The Air Pirates WW2 site

Fokker - simple WW1 aerial rules

Instant Spandaus - WW1 Rules from Nigel Lancaster

Knights in the Sky - WW1 aerial combat by David North

WW I Aerial Combat (1914 - 1918 AD) - Fast Play Rules for Students, by Matt Fritz

Zeppelin Battles of the Great War - Airship combat (!)

Zeppelins Over London - More airship combat! Part of the Junior Generals series.

WW2

Flight Squadron - Ultra-Simple WWII Air Combat

WW II Aerial Combat - Fast Play Rules for Students, by Mic McGoldrick and Matt Fritz

Hunters in the Sky - WW2 aerial combat by David North

Instant Bandits - WW2 rules from Nigel Lancaster

Minimal Aerial Combat - Quick and simple rules by Pete Jones

RAF Aircrew - WW2 based aerial RPG by James Kemp and John Rutherford

Battle of Britain Campaign Rules -

Mustangs - The Air Pirates WW2 site (also WW1 and Moderns)

Modern

Air Wars - Simple air to air combat in the jet age

Mig Madness: Jet vs. Jet combat - Fast Play Rules for Students, by Matt Fritz

Air War: C21 - Modern fast play rules (site)

Instant Thunder - Innovative modern rules by Nigel Lancaster

Mig Hunters - Post-WW2 aerial combat by David North

Mig Alley Ace / Phantoms - Modern rules on the The Air Pirates WW2 site

Phantoms - An excellent set of modern hex-based rules by Dave Schueler, inspired by AH's "Mustangs" game.

----- Intruders - Vietnam supplement for Phantoms

SF/F

Aeronef - Victorian Science Fiction

Hard Vacuum - a fast, furious game of primitive rocket combat.

Star Hunters - An SF version of "Hunters in the Sky", by David North

Star Wars: Silent Death - Adapting the "Silent Death" rules for the Star Wars universe.