Check Your Six! (1:300 scale aircraft)
World War 2 1:300 scale:
www.heroicsandros.co.uk/heroics: this will be the new website for Ros/Heroics. My collection is predominantly Ros/Heroics, which has been sold recently and is not available for direct order as of the time of writing (1/4/2010). It was sold by Navwar, but should be available shortly.
www.nobleminis.com: these guys make a few bombers and some prepainted fighters.
www.ghqmodels.com: technically these models are 1/285th scale, but they generally work in the scale.
www.raidenminiatures.co.uk: 1/285th very precisely cast Battle of Britain and some Pacific models.
WW2 and Modern 1:600 Scale
www.picoarmor.com: I have recently become a convert of Picoarmor/O8 figures in 1:600 for both WW2 and modern air combat. Their line is quite extensive.