This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Which part are you having problems with - getting the data from the DB, creating an Excel file, streaming the file to the browser, or emailing the file to the user?
For creating an Excel file you can use a library like Apache POI or jExcelApi. You can't stream the file from a JSP, though, because JSPs can't handle binary content. You'll need to do this in a servlet.