I haven’t been able to access the 2dBoy blog for some reason, but I trust that Rock, Paper, Shotgun has reported this accurately: Kyle and Ron have released sales stats for their birthday sale experiment. During the week-long sale you could pay whatever you wanted for World of Goo.
Not surprisingly, the vast majority of people paid $2 and under. But I think things worked out well for 2dBoy in the end – they made 57,000+ sales and generated $100,000+ in one week. Not a bad present for the young game (and its proud papas)!
A survey that players could take after purchasing the game reveals more interesting information.