I'm looking for an Excel spreadsheet I can download that contains
most, if not all, the comics Marvel printed. It should at least have
the main ones. I found this already for DC comics, but was hoping to
find one for Marvel. It should have the name of the series, year or
volume number, and issue number for column headers.  It can contain
other types of comics as well as Marvel. Thanks.

http://www.comicspriceguide.com

The site will let you keep track of your collection online. It has a
list of all the comics from marvel, dc and lots of others. I don't
think theres a way to DL an excel sheet of it, but there are forums
there you could try.