Not that I'm aware of. You can't actually edit  and save data back to the Excel
source workbook using Excel Services. Like you say you can add parameters to
your Excel workbook and then users can perform calculations run-time in Excel
Services but the data doesn't get saved back to the source. If you've got the
Excel workbook within a document library then whenever the file  is checked out
it'll be locked to other editors.

This sounds like an ideal situation for PerformancePoint Server 2007 which does
enable you to selectively distribute Excel workbook authorship and have
concurrent updates performed to a workbook by different users.

I am attempting to get excel  Services to work properly on my test
deployment. Everything is activated, and the settings are set
according to microsoft's specs. After i upload  the spreadsheet and
publish it to excel services, i added the library to the trusted
sites. I tried to open it in the browser and i get the error message:

"You do not have permissions  to open this file  on Excel Services.

Make sure that the file is in an Excel services  trusted location and
that you have access to the file."

I googled the error and saw that i need to make sure my settings are
correct and the it is set to Process account and not Impersonation,
which i had already switched.

Has anyone hit this problem and gotten through it? I am stumped.

Check the library URL in the trusted sites, make sure that you add the URL of
the library (without the reference to the view, i.e. /Forms/current.aspx).