DHH writes about how to shake up tech publishing:

At 37signals, we optimized for a niche seller by writing all of the content for Getting Real in Writeboard. Then Jason spent a little week marking those 200 pages up in InDesign. Then we spent a day building a dead-simple shop in Rails that would take $19 from your credit card and give you a PDF. […] That scenario worked well for Getting Real, which was all short essays that you could print out if you liked or even read on the screen without too much distress. And in just three weeks since its release, we’ve sold over 5,000 copies. You do the math. Even at such “low” levels, it’s comfortably profitable.