Basically... to people who enter data into those 200-and-more-input-controls UIs, accountants who do horrible stuff with excel, secretaries who struggled hard to learn how to create a standard letter in MS Word 2003 and don't want to go through this experience every odd year and developers who run Visual Studio, a browser and fiddler side by side on two or three 24'' monitors. Ah, and last but not least businesses who are not very eager to write of billions in licenses and custom applications...