I don't know how to evangelize Web 2.0

I just got back from a Christmas party thrown by my old boss, Bruce Twickler. I also got to talk with a couple of other people from Andover.net and one of its earliest investors. These guys were all true Web 1.0 pioneers, so they know what a real wave looks like. They also know me and trust me enough to understand that if I am really excited about something it must be hot, and yet I was unable to explain exactly what changes would be brought about by Web 2.0 techniques. Frankly, tagging is an extremely weak thing to explain, and collective bookmarking and looking at other people's pictures also sound scarily geeky. One thing that did resonant with them was the idea of moving your identity online. Whatever that means. We need some really hot exemplars. Google Maps may have caught some people's attention, but there have to be several more killer Web 2.0 apps to really get the public excited. Does anyone have a way of explaining the changes Web 2.0 will bring to the majority of Internet users in the next couple of years that doesn't involve a multipoint bullet chart? I need one sentence and five sentence explanations.