This is information I posted some time ago but I have had several people ask me about it so I feel it is worth repeating.
The Yardsaletreasuremap site is pretty amazing. You type in your address and you get a map showing you where the yard sales are in your area. Not only does it tell you where they are, it has the date and description of the yard sale!! To get the information on the sale, you need to click on the balloon with the number on it.