I just realized something: Dr. Strange exists in the Marvel movie-verse already, or maybe just the Spiderman movie-verse. I don't know if this means in a comic, or the actual Steve Strange. Jameson mentioned him in SM2, when they were thinking of a name for Doc Ock. Again, he might just mean the comic book character. But who knows? The same thing with Superman in the 1st one, when Aunt May refers to him. Same thing, it might be the actual Superman, or she could be referring to the comic. I know a crossover is near impossible, and to be honest I don't really think one would work in any superhero movie right now, it would change the mood, but its just something to think about.