Hi:
This falls under the category of creating your own custom "front-end" to the BI platform, using .NET or Java or ...some other language or the AppDev Studio Java Beans (SAS's tool that lets you develop Java applications and JSPs with Eclipse). For example, if you use AppDev Studio's Java Beans and develop a JSP, then you can deploy that JSP from the Information Delivery Portal.
The kind of custom application or report menu that you envision. Would not run inside Web Report Studio -- so I'm not sure it's going to have the utility that you're looking for. On the other hand, you might design your own custom portlet to replace the default stored process navigator that comes with the Information Delivery Portal.
Or, you could use Dynamic HTML and JavaScript, PHP, etc to design a web front end that executed stored processes using the Stored Process Web Application. You probably want to look at the documentation on BI Web Services and the .NET or JAVA examples that it contains. Some links:
http://support.sas.com/rnd/itech/doc9/dev_guide/websrvcs/index.html
http://www.sas.com/apps/forms/index.jsp?id=wp&cid=3540
http://java.sun.com/webservices/
http://msdn2.microsoft.com/en-us/webservices/default.aspx
cynthia