Custom Properties for RDL
In SSRS, each report has a set of default properties. Little known is the capability to introduce your own properties, which can be used to help you classify or categorise reports especially if it's integrated with your LOB applications.
It's actually quite simple - Make use of the SOAP API - Microsoft.SqlServer.ReportingServices.ReportService2005.SetProperties
I've extend on the sample SSRS Application Sample - RSExplorer to demonstrate how you can set the properties, which can be retrieved easily.