Being one of Marvel's big screen "Avengers" has its advantages. Sure, you've got to fight off an alien invasion or a cartoonish supervillain from time to time, but in between those gigs you'd be doing all right. Robert Downey Jr., Marvel's go-to franchise superhero Iron Man, is set to do rather well for himself in light of the billion dollar-plus success of "The Avengers." Earth's mightiest heroes: Saving the planet and getting paid.