Having had to read, digest, and regurgitate all three of the above references, each has its own unique viewpoint. Forester's Effective Cycling is probably still the most influential, mostly because it was the driving doctrine behind the whole vehicular cycling thing, especially the LAB's Effective Cycling training program (now called "Bike Ed"). Forester's book was meant to be a one-book-fits-all comprehensive reference on bicycles, to the extent that it not only tallks about traffic safety and hazard avoidance, but Forester throws in long sections on the anatomy of 70's and 80's model road bikes, wiring up hub generators & bike lights, reviews of cycling-themed novels and movies, and even how to find & romance your sweetheart via bicycle (you have to read pretty far through, but believe me, it's in there). It's a good book, but John Forester is a very opinionated man and you have to wade through all his rants in the book. Some say that's the fun part of reading Effective Cycling, though...

Robert Hurst's The Art of Urban Cycling was the book that introduced me to vehicular cycling and got me interested in those sorts of issues, as well as changed the way I ride when it came out back in the summer of 2004.
Hurst writes from the viewpoint of a bike messenger, one who takes his bike and his bike out in the streets every day to mix it up with traffic, and so trusts nothing and no one with four wheels and a mechanical motor. Hurst starts from the viewpoint of the Vehicular Cycling Principle ("Cycists fare best when they act and are treated as drivers of vehicles." -- Forester) and then notes that our communities have also furnished us with bike-specific facilities such as paths, bike lanes, etc.. The Art of Urban Cycling tells us that as bicyclists, we enjoy the best of both worlds -- we can behave as vehicles per the Effective Cycling principles and your bike will take you anywhere that your legs have the power to pedal it, and at the same time we can also take advantage as convenience and the situation at hand dictate, and thus avoid much of the motor traffic while maintaining a Zen-like state of mind. I like the book, and refer to it a lot both in my personal riding as well as the LAB classes.

The book Lisa mentioned but declined to name is Dave Glowacs' Urban Bikers' Tips & Tricks: Low Tech & No Tech Ways to Find, Ride, and Keep a Bicycle. It's been around for about ten years, last updated in 2004. Oddly enough from the book's content, Dave is an LCI in Chicago, IL. As Lisa mentioned, Dave covers a lot of the Road I and Commuting course material in here from the LAB curriculum, but he also adds in a lot of the alley cat/impatient bike messenger tricks that can quickly turn a cyclist into road kill or somebody's hood ornament. I like this book too, but I'll quickly admit and admonish that there's a whole lot of stuff in this book that I don't recommend, or do (at least when there are witnesses around...)

Tom