'The War Of The Century - When Hitler Fought Stalin' is still one of my favorite docs. I like how it shows the whole of Europe getting drawn into total war just because 2 insecure paranoid psychopathic neighbours can't get along.
Recently found the Military Channel's series 'Great Planes' on Piratebay. I'd seen only one episode on TV and I liked the fact that they spend a full 45 minutes on one plane, its history and its legacy. Of course they should've named the show 'America's Great Planes' since it only covers US planes, but to be honest, especially after WWII the US simply lead the way in plane design.
Apart from that it's a nice and informative watch. They make sure that the plane-of-the-week gets put into its historical timeframe/context, so in the P-40 Warhawk ep. you get a lot of stuff about the Flying Tigers for example. Also other rival planes get covered.
The format can be a bit obtrusive though. While there is a ton of unseen stock footage the editing of the show can be quite distracting. Also the show's host has to be one of the most ill-suited people to host a TV show. It's a former fighterpilot who has clearly been hired for his looks. No real interview skills (tendency to repeat stuff what the other guy just said, stuff like that) but to be honest, he is just a proper nerd who doesn't really handle people that well. And it doesn't help that the guys he interviews are also (mostly retired) fellow plane nerds (mechanics, pilots, etc.). So it's forgivable. ;-)
So if you can stand the occasional awkward interview and some in your face editing, this is quite an informative show.
List of episodes: Skyraider//Warhawk//Mustang//Mitchell//Eagle//Falcon//Hornet//Catalina//Blackbird//Thunderjet//Starfighter//Super Sabre//Huey//Phantom//Stratofortress//Corsair II//Invader
Altough the one I saw on TV was about the B17 so there are maybe already newer episodes out. There should also be one about the P39 Airacobra.