According to this article, they did a test where they subjected several male test subjects to various smells while measuring the signs of blood flow from sexual arousal, and it turns out the smell of PUMPKIN seemed to be the most stirring (if you'll pardon the pun) of the bunch they used. Sadly, it doesn't lists the scents they used in the experiment, just that there were 24 of them.
I get the feeling though, most women already know that the smell of good cooking is always a way to get men interested.
NOW, what I want to know is what scent has the same effect for the other gender? That way I can figure out what type of cologne (or whatever) I need to start stocking up on.