I just hope it isn't too expensive if you have to pay real $$ to get game credit. If you assume an average sale price of $50, with 20M+ copies of COD6 sold, there's $1BN in sales - now I know the developers don't get all of that, but they do get a pretty hefty chunk. Here's hoping greed doesn't result in these extras being priced out of most peoples reasonable spending limits....

EDIT: Sales are WELL over the $1BN - I just read that they hit that 10 digit sum back in January of this year so it'll have long since passed that by now...