The Starbucks ( SBUX)mobile experience drives traffic and loyalty at its stores as well as a good chunk of my bullishness on the company and stock. The more I use this app, the more it impresses. Of course it lets you pay via your mobile phone and collect rewards to achieve green and then gold status. That gets you perks, such as periodic free drinks. When you dig into this thing, you find you can do all sorts of cool things like filter the Starbucks' food menu by ingredient. So, if you're allergic to shellfish or soy or peanuts, you can eliminate items that contain those ingredients. See Also: Another Katie Roof story that runs down the Top 5 Holiday Shopping Apps this season.