I'd like to see a few things as an rpg or a setting with enough house rules to make it work.
Dune by Frank Herbert
Codex Alera books by Jim Butcher
The Elven Ways by Jenna Rhodes (not a very good series, but amazing setting and world)
Magic: the Gathering
Spyro the Dragon (admit it, it would be fun)
Fallout (every time I play New Vegas I think I want to make it in Savage Worlds. Fate could work too)
Lego (either the film or the video games)
I agree with several of these. Would love a Codex Alera rpg and Dune. I think Grimm could be a nice urban fantasy rpg.