I don't know if any of you have read The Art of Urban Cycling or not, but I found it to be informative and humorous enough to make it a quick read.
Being relatively new to riding on the roads, I found most of it to be pretty eye-opening. It pointed out several bad habits that I was developing. I also enjoyed the comparisons between the "vehicular cycling" vs. the "invisible cycling". Actually it turned out to be a healthy mix of both was prescribed.
Maybe you all could recommend other books that proved to be useful as well.