So like most fans of Marvel's Avengers we too had that urge to see a cameo from Andrew Garfield as Spider-Man (see Spider-Man Rebooted Too Early?).
However we've also come to the conclusion that the funnier cameo would have been Captain America himself, Chris Evans, portraying his Fantastic Four character Johnny Storm, aka Human Torch.
Like Spider-Man the Fantastic Four are also headquartered in Manhattan New York, so it would make perfect sense to have Chris Evans show up as Johnny Storm to see if the Avengers needed the Fantastic Four's help.
Come on you know you'd have laughed at this too.