I'm not sure how i'd never heard of alexa's web rankings before, but if you put in a url it'll pop up a description with a ranking which is made by the number of hits by people using their software. If you've ever wondered whether more people read the new york times online or shop at amazon, now you can find out (amazon is 22nd, while new york times is 82nd).

Also there's a convenient, "people who liked this site also visited" feature a la amazon. Which reminds me of a post today on the Volokh Conspiricy:

This case aside, I love the "readers who are reading this are also reading that" function of Amazon, however incomplete it may be. I don't buy all of my books online, or all on Amazon, nor are all of the books I buy online for me, but the service provides some amount of information. A friend once made the seemingly obvious but brilliant suggestion that Amazon merge its database of reader's preferences with an online dating service.

Give me a man who is reading Solzhenitsyn's Cancer Ward, Jennifer Weiner's hilarious Good In Bed, and The Dictionary of Insurance Terms, and I'm there. Of course, we don't want this model to be taken too far:

"Men who have enjoyed dating Suzy have also enjoyed dating Kelly and Sarah . . ."