This allows you to open the link in a new browser window or display a pop up a message box.
I will sometimes use pop up message boxes on the column headers to define what the data definition is. This is the syntax:
="javascript:void alert('This is a test column header alert')"
To open the link in a new window, use syntax similar to this:
="javascript:void window.open('http://servername/reportserver/pages/reportviewer.aspx?%2freportfolder%2fReport+Name&Parameter1=" & Fields!Field1.Value & "&Field2=" & Fields!Field2.Value & "&rs:Command=Render','_blank','resizeable=1,toolbar=0,status=0,menu=0,top=20,left=20,width=740,height=730')"
peace