This sounded fun, so I had a look on the web and I found two that worked;
This site
http://www.ean.ch/gepir/client_e.asp
provides the infomation about the company that provides the product, according to the barcode, but no infomation about the product itself. This one uses many differnet types of barcodes, but most of the ones you will be looking up will be the 13 digit barcode.
This site
http://www.upcdatabase.com/itemform.asp
gives more infomation about each product, as opposed to the company that produced it. I just tested it with a can of WD-40 and a jar of Tesco Jalapeno peppers, and it didn't recognise the peppers, (only that Tesco made them), but it knew the size & weight of the WD-40 exactly.