Learning Web 2.0

I recently began to work on a new database system, Cloud DB. It will support, among others, Web 2.0 applications, such as social network. I know what they are (I think), but to better understand them, I decided to have some first-hand experience on them -- the feel, features, real-time performance, gadget applications, and so on. Below are my first Web 2.0 applications.

- Blogger (this site)

- Facebook

- LinkedIn

- Dopplr: social travel log