LogiXML's LGX Report lets developers create and publish rich dynamic online reports quickly and easily.

+ Drill Down Reporting
+ Cross Tab Reports
+ Charts and Graphs
+ Advanced Data Retrieval
+ Data Grouping
+ Dynamic Sorting
+ Export to Excel, Word, CSV and HTML
+ Low Cost PDF Export available at the LogiXML store

Built on XML technology, LGX Report lets developers create full-featured web-based reports using a drag and drop user interface. The tool can connect with numerous databases and web services and can be deployed across any .NET architecture. Various add-ons are available too. Check it out. It's pretty popular.