Keep Circulating the Tapes: Until the last couple of years, there were very few Captain America trade paperbacks and those few that did exist were reprints of recently published stories. Since then, the last year and a half of Steve Englehart's Captain America run (the Secret Empire and Nomad stories) have been collected, along with all of Jack Kirby's 70s Captain America run, key storylines from Mark Gruenwald's Captain America, and all but one key issue of Mark Waid's first Captain America run (omitted as it is part of an Old Shame of Mark Waid, even though it contains major plot advancement for his Sharon Carter storyline).
What Could Have Been: J. M. DeMatteis wanted to have Captain America stay an 80 year old man/give up being Captain America to be a peace activist in Captain America #300 and have the issue end with Nomad assassinating Cap, in order to shame the US and the Soviet Union into embracing peace. Oh and a recently introduced character known as Black Crow (a Native American hero) would have become the new Captain America.
Roger Stern and John Byrne once pitched a "Bucky Returns" storyline where Captain America would find that Bucky Barnes survived the plane explosion, but had lost his arms and legs and was disfigured (but not Johnny Got His Gun disfigured, as far as Bucky simply having his face burnt and having full speech/hearing/sight). Bucky would call for Captain America after finding out that he was going to die, leading to a tearjerker scene as Cap would be reunited with Bucky to say hello to him, before dying.
After his return in Captain America: Reborn, Steve originally was going to take the Shield back. However, seeing that many fans had grown to love Bucky in the Role of Cap, they decided to let him be Cap. So they temporarily shared the title.
Cap's original name was slated to be "Super-American", but Jack Kirby & Joe Simon decided on "Captain America" for the name, citing that there weren't enough "Captain" superheroes.