The good folks at XKCD.com created an illustration of web 2.0. This is a representation of the current state of the social internet represented by a cartography style of 15th century map makers like Amerigo Vespucci.
See a hand drawn map showing all your favorite websites, with size displayed by prominence. Displayed is a list of websites I know by heart: myspace, facebook, classmates.com, friendster, wikipedia, live, yahoo, eharmony, youtube, world of warcraft, orkut, flicker, P2P, last.fm, usenet, digg, fark, reddit, stumbleupon, sourceforge, reunion.com, piczo, AOL, and cyworld. Oddly missing is Google, but I guess this could represent the Sea of Culture. Or maybe the culture is just bacteria.
Here is the map of the web and related points of online interest:
An attention-grabbing discussion of online community growth is worthy of comments.