The Rocketeer and The Invaders

Captain America's war years were covered quickly in a few scenes and montages in his first movie.  Now that Marvel is on the verge of acquiring most of its characters, a flashback Invaders movie could actually happen - and be very cool.  Of course, the one sticking point would be Namor, who's rights are still tangled up with Universal Pictures, but perhaps a deal like was done with Spider-Man could make it work.