I meant to mention this previously, but Blogs of the Day is the latest link popularity site. It’s rather nifty in that it ranks sites and articles based on actual readership, and in the fact that it’s an opt-in system. It also only keeps statistics for 24 hours, in keeping with the ephemeral nature of popularity on the internet. Various lists are provided, including Top Posts in the last 24 hours, the BuzzList (most popular in the last hour), Strongest (posts which have remained in the statistics the longest), and Weakest (posts which will fall out of the 24 hour window if not visited soon), among others. It also tracks the categories of the posts.
Currently, it’s only usable on WordPress blogs, but hopefully they’ll come up with plugins for other systems soon, and expand their user base.