Grocery Guide.com
From Read/Write Web:
Utah-based GroceryGuide is a local information site that aggregates grocery store sale circulars and local coupons from around the US and makes them searchable. The site also rates sales based on 19 years of grocery store sale data and displays a historical price chart (which goes back almost 2 years) next to each sale item so that you can see if the deal you’re getting is really a deal — according to GroceryGuide, just because something is on sale, doesn’t necessarily mean you’re getting your money’s worth.