I've just started reading Getting Real by the good folks at 37signals. So far, it's a pretty interesting read. For those of you not familiar with 37signals, they are the folks behind some of the more popular web apps like Basecamp, Highrise, etc. We've been using Basecamp for a long time here at Centrro and I've used it for some of my side projects. What I like most about their apps is the clean design and attention to detail re: UI.
Back to the book, it's a primer of sorts for building web apps using agile software development. Though we have a pretty lean shop here, I can see the advantages of actually getting even leaner. Not in head count but in how we develop new products. Fewer meetings, very quick/general spec docs, faster and smaller product roll outs, etc. I highly recommend this book and the price can't be beat!