In case you missed it, the NY Times published this article on how keeping your neck cool (click for link) can improve athletic performance in the heat and humidity, although it may come with a risk (but what worthwhile pursuit doesn't?).
So it looks like the ice sock, or my preferred version, the ice bandana, has some scientific support. In case you've never used either, here are the simple DIY instructions:
1. To make an "ice sock." - Take one tube sock, (a least calf high, if not longer) and fill with ice. Drape around neck or down back.This look will also get you "old school" rando cred on many levels - including fashion sense.
2. To make an ice bandana. Fold a bandana in half on the diagonal. Place ice in the fold, cupping the ice. Roll bandana around ice. Tie bandana around neck. Though much less fashion forward than the ice sock, the ice bandana is very easy to refill at a fountain soda dispenser and when the ice is gone, you are not wearing a tube sock around your neck or draped down your back. That may be to your liking.
Try it, you can thank me later.