A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
You can create a parameterized query using an Excel worksheet cell as in
Query 4 -- A parameterized query to list of customers in a zip code that is specified dynamically
http://www.tushar-mehta.com/excel/newsgroups/rdbms_in_excel/build_query_4.html
I don't know if you can use a PowerPivot grid cell in place of the worksheet cell.