Google Analytics for Facebook Fan Pages
WebTrends Analytics for Facebook
Firmly aimed at the high-end market, WebTrends makes intriguing promises about the level of data they can collect, despite the lack of scripting and caching of images. I'm very curious as to how they manage it, I may need to look at a page using their analytics if I can locate one. They're offering a webinar on March 3rd if you want to see a live demo.
I haven't used wither of these myself yet, so I'd love to hear about your experiences with them, or any other alternatives you'd recommend.