Free as in beer.
Free as in "you don't pay nuthin'"
How you may ask?
Well, it appears that Google is offering a $10 signup bonus if you open up a Google Checkout account and buy something.
So you do the math. Then signup using the link above. Then go here and nab yourself a game.
$10 signup bonus for Google Checkout - $9.95 for one of my games = FREE FREE FREE
Note, your mileage may vary. On the aforementioned signup page, there are loads of GC-enabled stores listed. I don't think the deal counts only for those stores, but I'm not 100% sure.
In any case, it's nothing outta your pocket, so give it a try.
Of course, you can always use that $10 worth of signup cash on something else, but looking at the list I think it's a good conclusion that my games are about the only thing that won't require anything outta your pocket.
They make great gifts! If you're an 18 year-old fanboy who only plays networked shooters, then give a copy of Duck Tiles or Bulldozer to your mom. She'll like it. Trust me.