Just to see what would come up, I typed in ‘cool web 2.0 sites’ into Google. One of the results took me here, to a San Francisco Chronicle newspaper article on this very topic, with my search term as the name of the article!
An Internet video ratings site and more called Dabble.com
I urge you to read the original article for all the details, but the article includes sites such as Dabble shown above, StumbleUpon which lets you discover cool sites others want to share, Slide for a slideshow of photos from popular sites like eBay or Flickr, Meebo to access multiple instant messaging accounts from a single web page and several more sites bursting with juicy Web 2.0 goodness. Enjoy! 
