I like the OkCupid-esque approach to data mining in this blog post. It's a great way to leverage customer data as a marketing tool. I'd love to see more posts of this kind going forward.

As for the data itself, I'd be interested to see which Yelp profile characteristics drive the most page views to the restaurant page (i.e. 4.5 stars vs. 3 categories vs. 500+ reviews). While the number of page views on Yelp may not be available, the number of click throughs to a restaurant's home page may be good proxy.