via
valentyna@ljQUOTE:
LJ Popularity uses Google's
PageRank algorithm to compute a completely scientific and objective number that determines how cool a person you are.
EDIT 1: ...OK, since people keep wondering, your 'popularity rating' is the probability of a user clicking on random Friends links to be at your profile page at any point in time. That's the essence of the PageRank algorithm—it's a traffic estimate based on the Web's link structure. It's presented on a logarithmic scale to make it easier to understand.
By the way, the median popularity ranking is 1.25/10. 50% of LiveJournal users are ranked above 1.25, and 50% are ranked below.