Steve Riley - Excellent Powerpoint presentation on Social Engineering Risks
The Powerpoint slide show is one of the most comprehensive presentations I've seen on the topic of Social Engineering. The human element is added as a level 8 to the classical OSI security model. The Powerpoint even includes some humor to keep things interesting throughout. There's also a podcast which is a 7 minute Q&A with Steve Riley on social engineering dangers.
Podcast and PPT links can be found here
Steve Riley - Defending OSI level 8
Powerpoint 7.2MB - 96 slides