Colloboration between T-SQL Table and Excel Sheet(s)
It's very easy to do this in access. Setup an ODBC Connection on the users computer then add in a linked-table into the access db. 

I don't think it would take too long for someone to create an application with a nice winform interface. We have one at my office where if you create a function/stored procedure in SQL starting with certain characters, lets say dbo.app_*******, it will appear as a report in the application and any parameters in the stored procedure will prompt the user to input a value in the app.