If you are or someone you know is upgrading from a point-and-shoot to a digital SLR or an interchangeable lens compact camera, you might want to look at or share this video series from Vimeo. The series, called "Behind the Glass," is an introduction to lenses and terminology.
Though they're geared for beginners, the videos are entertaining enough that even people who understand how and when to use a particular lens might want to check them out. The videos are targeted at those shooting movies with their cameras, Vimeo being a video-sharing site after all, but much of what's said applies to still photos, too.
You can check out the other two videos in the series over at the Vimeo Video School site.