I did an online training (free) by the American League of Cyclists called "Online Bicycle Education Traffic Skills 101" which was 4 chapters. The website says it takes 4 hours and it took me about 1 hour to do all 4 chapters. I am a fairly astute urban/street rider, however I learned a lot! I highly recommend it. Here's the link if you're ever interested:
http://www.bikeed.org/