37signals has published their latest book, Getting Real, as a PDF download that they are distributing themselves. After more than a day, they've sold over 1750 copies at $19 apiece:
That's exciting. These numbers demolish the sales pace of our first book, Defensive Design for the Web, which was released through the traditional publisher/bookstore model. DIY publishing: There's a new sheriff in town.
If you do the math, that's ~$33,000 in sales in one day. I don't know what the advance would be on a book like that, but they've got to be approaching it, and if/when they reach that figure, the profit margin on subsequent sales will be much higher than the royalties paid by a publishing company. Interesting experiment.