I’ve rather belatedly discovered Quantcast – which tracks a good chunk of the web, but is very US-centric. One thing it does do though is track every WordPress.com hosted blog, including, for what it is worth, mine:
There is plenty more there – have a look around and try your favorite site. There are plenty of other bloggers that use WordPress.com – such as Rowan, dimpost, Poneke, Open Parachute, and home paddock. I confess to not reading any of these aside from Rowan’s – I got them from a list of top NZ blog sites compiled by Tumeke, of which more later.