This one by Adrian uses a few more criteria, ranks more blogs, and can be easily updated!
He notes that there are still bugs in the system — plus, in the near future, you will be able to submit your own site to the list and sort indivudual columns. When it’s really up and running, it’ll be a nifty little tool.
Again, popularity in the blogsphere is like popularity in high school — the most interesting blogs may still be undiscovered and the higher-ranked blogs may not be your personal favorites. But the list is one more way to see what’s being read and which bloggers are useful to contact if you want to spread some information.