This is a storehouse for Golden Age characters(not retcons) that appeared in a modern comic. Now, I'm not going to list every appearance of Namor or Cap, but you should get the idea.
USAgent(limited series)#4-The Angel, now an old man is responsible for the Scourge program. The Angel is poorly characterized, and the limited series as a whole is poor quality work.
The Blazing Skull
Captain America(issue unknown)-The Blazing Skull is revealed as immortal, and he helps Cap overcome the British Bone Brothers.
Midnight Sons(issue unknown)-In one of the numerous crossovers, Blazing Skull has a nice little conversation with Dr. Strange, and then sends some of Lillith's demons back into hell.
Captain America(numerous issues)-Even though Bucky's dead, his ghost conviently haunts Cap to provide a throwaway soul-searching issue.
Captain America (1st series)-The original, the only the only Captain America. If you haven't heard of Cap's modern adventures, then shame on you!
Captain America (Heroes Reborn)-The less said, the better
Captain America (2nd series)-The series is rather new, but shows some promise
-Cap has also made guest appearances in about every modern title Marvel has ever published.(including NFL SuperPro. Really!!)
The Avengers(pre retcon-beginning with #57)-Surprisingly enough, THe Human Torch was orignally supposed to have been The Vision.
Heroes for Hire(all issues)-The Torch's flame has been extingushed as he now acts as Iron Fist's boss.
Fantastic Four(1st series)-The Tinker brought Toro back to life to fight the Fantastic Four. The Fantastic Four accidentally killed him during the battle.
Avengers West Coast-The Avengers from the West Coast ressurrect Toro once more and all the shenanigans start up again.
THe Sub-Mariner(1st series)- I'm unfamiliar with this series, so I'll leave this one be.
Namor, the Sub-Mariner(2nd series)-The more modern series, with some good artwork and decent stories.
-Like Cap, Namor has made more than his fair share of appearances in the Marvel Universe