The powers-that-be have yet to announce who they'll be casting as the iconic titular character in The First Avenger: Captain America, with names such as Chace Crawford (too pretty?) and John Krasinski (umm...nope) popping out. At the earliest stages of speculation, when Brad Pitt's name was being tossed around as the ideal Thor, Leonardo DiCaprio was being mentioned for this role. Leo's my favorite actor, so I wouldn't mind if it came to that, but I don't think they'll go that way.
There's another actor, recently surging in popularity and Oscar-nominated to boot, that I believe would be a very good Captain America. He's American (as the character's actor should be), a good actor, and he starred in an action movie with American sentiments (just something called The Hurt Locker). He's being rumored to be Hawkeye in the Avengers movie, but I'm thinking that might be a decoy...
And who else to play Nazi villain Red Skull but Christoph Waltz?