The Web 2.0 sites are divided into social networks (like MySpace), social media (user-generated content like Flickr), webware (applications that work within your browser), aggregators (My Yahoo style), mashups (such as sites that add features to Google Maps), and Internet TV (like YouTube).
Launch Photo Gallery - Around the Web 2.0 world in 23 clicks
Source: Where to find the world's hottest startups