Personally, if I had to spend it on the game, rather than living expenses, etc (so I could quit my job/school and just write games all day) I'd probably divvy it up into quarter-mils (1 mil = 4 games) and get professional artists and musicians to work on my game full-time as I sit back and hack away. Then I could hire some games industry consultants to root out bugs and whatnot, and figure out how to spend some money to get some representation.
Then, I'd go to IGF and have everyone scream at me for being a filthy traitor to the 'indie way' because I spent big money on it.
So what game(s) would you build with a million dollars?
First. I would invest 500,000. Then, I would shoot for making a role playing game graphically similar to Baldurs Gate II. I would take it to IGF, win, publish it, sell it, use that revenue to create a 3D version of my original concept with the revenue I made off of the first game or the interest that I earned off of the 500,000.