The science of movie chemistry. I would be really interested in this because it strikes me that so many romantic comedies stumble at this, the most important part of the process: the casting. Unfortunately the article is a bit of a gyp because it seems they are only willing to put their cards on the table after the fact.
This is also interesting to me because last night myself and Magnus brainstormed a perfect romantic comedy, and the next question is what to do with it. Man alive it was good though.