Users can use shared datasets in SSRS. Depending on your budget SAP BusinessObjects is really nice for adhoc reports for end users as long as the admin builds the universes correctly. It's web based, you define the object names to be common business names and the users don't have to be familiar with joins or other structures in the database. It's drag and drop into a view area and a filter/where area and it's very intuitive. It's also very expensive.