Steve Krug is the best writer I’ve ever encountered on usability and Web design. His first book, Don’t Make Me Think, is one of two books on Web design I ever recommend. (I just ordered his second book, so that number could jump up to three.)
This 60-minute presentation is a little slow getting started, but if you’ve got the time, it’s a good overview from one of the clearest thinkers in the industry. Hat tip to Ryan at 37 Signals.