This is a "dream project" that I'd like Marvel to do and make available for purchase by me, just to clarify, not a dream project I'd like to do at Marvel. Although if they want me to help, I'm open.
Because it would be kind of ambitious. My idea is for a series of books collecting the entire Marvel Universe in chronological order. Everything they've ever declared to be canon, starting from the beginning (and yes, I know that would involve the Golden Age Timely stuff) and moving all the way up to the present day, by which time of course they would be years ahead because there's no way you could keep up with the material.
I'd like to see it as big, thick hardcovers, somewhere in the neighborhood of 15-20 issues per book, just going month by month through Marvel's output and collecting as much as you can cram in one series. You wouldn't do it in the order it was set, obviously, or continuity inserts would eventually make it an incomprehensible nightmare--you'd probably need to jump around from series to series a bit, though. So one volume might have three or four issues of "Fantastic Four" that all occur as part of a single series of events, then jump over to a 'meanwhile...' set of issues in the X-Men that are meant to be roughly contemporaneous. (Perhaps even get a Marvel historian to annotate the whole thing with the reasons for placing issues in a given order?)
Obviously, it'd be huge, unwieldy, only-for-collectors, and probably desperately unprofitable. Still, I can dream of having the entire Marvel Universe spanning my shelves, can't I?