I am developing an Excel Viewer app for Android that will support any Excel file in the app with user friendly viewing capabilities and features like Charting, Annotation etc. Should I focus only on MS Excel viewer (skip the editor since its a crowded market?), the app may cater to users who have a need to only view Excel sheets everyday (MIS Team, Middle and Senior Managers for decision making). The app could be used to view, analyze and collaborate on the Excel. Some nice features for viewing, first level analyzing and collaborating??? Do you see a market here?