Does this service exist?

I want a web service that will let me search local retailers for an item.  I know that there are services like this for *online* retailers -- you search for an item and it tells you all the websites where you can buy it as well as the prices. 

However, I want one of those for the physical world.  It's an extremely common situation -- I want item X and I need it today.  Where can I buy it?  Most stores already have a matching website that will let you search for items sold in their physical stores.  Can't someone put that data to some good use and build a physical retailer search engine?