WEB 2.0?

yo. i don't know how many of my friends and people who read this site are all nerdy mcnerdface like me, but for those who care, can we talk about web 2.0 sites? listible seems to be a good collection of web 2.0 sites out there and i have to say consumating is fucking rad (thumbs?) in it's functionality and use of ajax/javascript/server stuff with the automatically appearing tags. obviously wiki/flickr/delicious/43things are the shit, but can you thrown in any other rad ones or sites that list rad ones? faves? there's a bit of web 2.0 discussion on williamsboard too. wiki notes: "Some of the more well known Web 2.0 entities are Google Maps, Flickr, del.icio.us, digg, and Technorati." now it's your turn!