Many, many people who run their own small business are undoubtedly familiar with Square. Or at the very least they have a passing familiarity with it. It's the sort of thing that's great for an artist selling their work at a show, or even an entrepreneurial babysitter, but some businesses need a bit more than that.
ShopKeep Mobile is meant to be that little bit more. It's a cloud-based system that uses Griffin's Olli hardware to provide business owners with a point of sale system they can carry around in their pocket. Registers can be set up quickly (accepting credit cards and cash), inventory can be tracked, and sales reports can be viewed in real time - plus it's integrated with QuickBooks. It can search through inventory, manage a customer database, use email receipts, adjust pricing for sales, connect with a printer for more traditional receipts and reports, includes a barcode scanner and a credit card reader/swiper, and can be used offline if necessary. Basically it's designed to be an alternative to using more typical register setups. Kind of like the Apple Store when you think about it.
ShopKeep Mobile is still in beta but you can register on the site to be kept informed of its progress. Of course there's also the slightly less mobile ShopKeep POS system for iPads that's already available if you can't wait to get started.