Like all good things this tradition started with Daredevil. While that was just a single, wrap-around anniversary cover, the inter-locking madness has already bitten Marvel's Spider-Man, Avengers, and X-Men titles with a healthy dose of eyeball-popping awesome.
Now It's Iron Man's turn. Feast your eyes on this; (click to enlarge).
The world of the Fantastic Four still tops my wish-list for who's next, but something tells me Marvel's looking towards the mighty halls of Asgard and Thor, God of Thunder. Talk about your win-win situations.