I'm not sure that this would fall into the "wide range" that you're looking for Steve, but here's my take on these:
Ordering for aggregates (used to allow subsequent framing options)
Framing (ROWS and RANGE window sub-clauses)
These two will allow one to perform "running totals", in a SUPPORTED, SET-BASED way. Now, running totals are frequently coming up here, and I definitely see these two as very highly desired. I personally would be happy to see just these two fully implemented to where running totals can be performed.
The other one that is highly desirable to me is:
Reuse of window definition using the WINDOW clause
This is just code re-use - it allows me to use the same windowing definition in multiple areas without having to redefine it everywhere. And if something needs changed, it only needs changed once instead of everywhere it's being used.
Wayne
Microsoft Certified Master: SQL Server 2008
Author - SQL Server T-SQL Recipes