Mobile shopping assistant Slice has a new tool that helps e-commerce shoppers find the best deals called Slice Watch. The service will allow users to track prices for items online and get emails if the prices have dropped. The tool supports retailers including: Amazon, Best Buy, Target, Walmart, Nordstrom, Macy’s, REI, Anthropologie, Newegg.com, Staples, Walgreens, and Sephora.