CrissCross
CrissCross is an open-source ASP.NET application that provides an alternative front-end for running SSRS Reports. That is, a way of running SSRS reports that is like the 'Report Manager' that comes with SSRS, but different and more customisable. It is built using the standard ASP.NET ReportViewer component and the SSRS web services.
It is also hosted on Codeplex.
For more details see the documentation at Codeplex.
