I've been thinking a bit about 4th edition D&D. I don't really like it for fantasy, but you know what it would be outta-the-box perfect for? Superheroes?
The more I meditate on the 4th Edition rules, the more similarities I see to classic comics, especially Marvel. Take the daily/encounter/at will power categories and map them to one of the quentisential Marvel heroes: Johnny Storm. His at will is a basic ranged attack- a mini-fireball. His encounter power are fire cages, while Nova blast is his daily ability. Ricochet shots, like Captain America does with his shield, or Cyclops does with optic blasts, or Daredevil's billy club seems like fairly typical encounter abilities.
The leader/lurker/brute split for monsters seems like a good match for Marvel villians. Magneto is a controller/leader type, while Juggernaut is obviously a solo brute- a massive amount of HP, great armor save and does 4th have damage reduction? Deadpool is like a lurker- stealth abililities, a short range teleport as an encounter power, and backstabbing like a rogue. Smells like lurker to me, and you could extend the definitition of Marvel lurker to guys like Green Goblin.
Anyway, it would take somebody more familiar with the system to convert 4th over to supers gaming, but if anybody wants to take a stab at it, based on this post, go for it.