Depends how much we're talking about here.
Probably buy a house. Maybe a new car (nothing fancy, something like a 2013 Golf).
Keep enough so I can be comfortable following my passions, and not have to be worried about money. And give the rest away. Though I would make sure that it actually goes where it's needed. Not just donate to charities where a chunk of the money will line an executives pocket.
Edit:
Oh and make sure some of it goes into building my death ray.
Can't forget about that.