Just stumbled across a website devoted to the artwork of John Buscema (1927-2002). He is one of my favourite comic book artists and is genereally regarded as one of the greatest of all time. Buscema combined the dynamism of Jack Kirby with lovingly rendered anatomy. This led to him being referred to as a comic book Michelangelo.
Buscema worked on superheroes (which he loathed) as well as romance comics and olde worlde adventure strips full of knights and wizards. But one of his favourite assignments was working on the Conan comics where he did some of his best work.
There's some great examples of his work on the site including paintings and sketches Buscema did for fun which reveal another dimension to his artwork.
And just for Simon here's some of Buscema's breakdowns for The Punisher.
Also just found a video of Buscema drawing Captain America. I've got this video as an extra on a DVD about superheroes and I love to watch it, gazing in awe as Buscema's pencil glides over the paper. Unfortunately Buscema died not long after the DVD was made. Although I never met him I was saddened to hear of his passing. The man was a true comic book master.