When using DataGroups, we can display the DataGroupKey in the DataGroupTemplate.  In my case, I wanted to display 3 additional fields in the DataGroupTemplate.

I was displaying checks sent to our vendors.  Each check had a list of what payments were included in the check (one check may be for several different items that needed paid to the one vendor).  I was grouping the data by CheckNumber.

In the DataGroupTemplate, I wanted CheckDate, CheckNumber, VendorName, CheckAmount.  In the ItemTemplate I had SubmittedDate, SubmittedBy, CostCode, Amount, etc.

So my request is to be able to use something like <%# Eval("CheckDate") %> in the DataGroupTemplate.