Pentaho Reporting is a collection of open source projects primarily
focused on the creation, generation and distribution of rich and
sophisticated report content from all sources of information.
Source : Pentaho
Now, with the combination of Pentaho Report Designer and BI-Server you can create report easily and deploy it to BI-Server seamlessly. In additional to that, all your reports can be outputted to Excel, Word, CSV, Web Page and PDF documents !