Here we'll discuss the importance of live, working prototypes that use real data and how to create them using nothing more than a Web browser and a text editor. Then we'll break out our laptops and hack some new functions--past SxSW attendees may recall "Kick-Ass Mash-Ups with Punk Rock APIs"--into a live page. This may sound crazy, but it's exactly how I prototyped the redesigned front page at Yahoo! and a bunch of fun stuff at Netflix.