In SQL Server Reporting Services (SSRS) there are two different methods for a user to sort their reports after they have been generated. Other folks have done a superb job of explaining each method, so I’ll just point you to their sites:
The user can interactively sort on a header textbox by just setting the “interactive sort” properties:
http://weblogs.sqlteam.com/joew/archive/2008/08/02/60666.aspx
You can also sort using standard report parameters:
http://www.databasejournal.com/features/mssql/article.php/10894_3492236