One nice and free dataset which you can play with is the BestBuy open data. You can download the full catalog of products from BestBuy in JSON and XML format.

One nice and free dataset which you can play with is the BestBuy open data. You can download the full catalog of products from BestBuy in JSON and XML format. http://developer.bestbuy.com http://developer.bestbuy.com Simply register for a key and you'll have access to the data.