Russ Chappell's Marvel Chronology Project features chronological listings of practically every character in the Marvel Universe. An excellent resource, a great group of folks on the boards, and I have to say I wouldn't have been able to even conceive of this site without it.
http://www.chronologyproject.com/
Also on the Chronology Project is Paul Bourcier's Marvel Calendar, which is exactly what it sounds like: an attempt to chronicle Marvel Time on a Calendar of Events. If that sounds familiar, it should. Paul is the Father of the Calendar Method of chronology, something that really clicked with me when I was trying to figure this whole thing out. Honestly, I have no idea how I would have pulled this together without it. Also, check out Paul's Avengers Year-by-Year Timeline on the excellent Avengers Assemble! site.
http://www.avengersassemble.us/
If you happen to be in Northern Illinois, swing by one of Amazing Fantasy Books & Comics fine locations. Or, you could visit them on the web: