This remarkable flash presentation not only teaches you how to bow correctly, it takes you through the entire complicated ritual of visiting a Japanese company, being introduced, presenting business cards, &c., accompanied by appropriate spoken dialog (with subtitles) and sidebars containing all sorts of relevant information (for instance, you should never write with red ink, since it was used for death sentences in ancient China and is considered highly inauspicious). Via plep.
For more information on various types of bows, including the extreme saikeirei, rarely seen since Imperial days, and appropriate contexts (“[A] bow accompanies all greetings and is a response to all offers, compliments, and a number of other behavioral patterns. To say Arigatogozaimashita ‘Thank you’ and not to bow is strange”), read the excellent little essay “Bowing, the Japanese Custom” by Tomoko, a student in Francis Britto’s English Composition class. I hope she got an A.