>
>Which does a nice job of passing the displayed value to the new page, but not what I'm looking for.
>
>Can this be done or will I need to handle it on the server side, resolving the natural key into its corresponding surrogate key or something?

You should be able to do this by changing the DataNavigateUrlField attribute in the source, or just modifying that value in the data grid's "Property Builder->Columns" builder (It's called "URL field"). You basically just point this attribute to any other field you want to use as the source of the parameter.

>
>On a related question, is it possible to pass mulitiple arguments to the page being called, e.g. values from different columns of the DataGrid?
>

Take a look at this link for some suggestions (from what I've seen, the answer is "No", not directly; but there are a few ways to work around this):

http://www.dotnet247.com/247reference/msgs/13/65344.aspx