I explored the winners of the 2007 Web 2.0 Awards for this item. Many are sites I've already discovered such as Craigslist, One Sentence, Picnik, Flickr, Pandora, Podomatic, Zillow, Etsy, StumbleUpon, iGoogle, Twitter, etc., etc.
When I saw Statsaholic, I hoped it would help me collect visit statistics for a podcast I post. I entered the URL as directed and was disappointed to discover it only tracked statistics for the entire web.mac.com domain and not my site on it.
I found other interesting sites on the awards list and will spend some time exploring them.