I like this article from Ben Huh from I Can Has Cheeseburger.

This one is poignant.

11. Measure the Number of Shared Experiences, not Users Try not to fixate on the number of users on your site. It’s much more useful to focus on the number of shared experiences. Admittedly, this is much more difficult to monitor but it’s a much more useful statistic.

I spoke about the LOLcat empire here last year.