Obama leads Romney in halloween mask sales 69% - 31%
This measurement is relevant because parents have a choice of how to spend their money. Also, young children reflect their parents' sentiments. This measurement has worked over the past 4 election cycles. It is pretty fool proof because people are spending their money for what they want, and it's not serious enough for people to try to manipulate.
The President will win re-election!
btw. Another key indicator to watch out for in the coming weeks, especially if Romney gets a "bounce" from his good debate performance where he lied profusely, "Regardless of who you support, best guess who do you think will win the election?" This question is more predictive than the actual horserace especially during chaotic moments. The President has been leading in this question all year long. I'll post a link when I find a new sample.