Microsoft Office 2007 is a great application development platform that enables users to continue using a familiar interface for interacting with business data and applications. Making use of the extensible UI, Workflow capabilities, connections to back end data using Business Data Catalogs, VSTO are just some of the features available to build your applications on the Office platform. An article by Moin on the MSDN site delves into OBA (Office Business Applications) in Retail.