Well, to explain my avatar, I must first explain my screen name. When I first started out online, my Yahoo account was Steve_Rogers_Captain_America. When I would register accounts elsewhere (to help remember them), I shortened that to "srca" and added 1941, the year of Cap's debut.
As for the avatar, back in 2004, after Marvel released the Masterworks debacle known as Golden Age Marvel Comics vol.1, I was approached to "try out" for doing some restoration work on the Masterworks. They were still trying to use fiche as source material, and sent me scans of several pages from Captain America to see what I could do with it. My avatar is my fiche restoration from page 5 of Captain America Comics #2. I never did get any work, but it helped lead me down the path that resulted in my Computer Graphics degree from Purdue last year, so my avatar both fits my screen name AND has personal meaning for me.
I also use it on the Collected Editions forums at MarvelMasterworks.com, and even have a couple of variations on it. There's my "Christmas Cap:"
http://images.yuku.com/image/png/a9a26df10364a956e5e829e43cd4f103d30d0ce0_t.jpg
And my "April Fools Day Cap:"
http://images.yuku.com/image/png/b51261f18f615965e89868e66335e852f87a5583_t.jpg
-Eric