It would be nice to be able to group by date with more granularity than is currently available. For example, group by month, or week, or day. The latter would be particularly useful (for me) when reviewing groups of photographs taken over a period of time. I can also see it being handy to quickly review what I did 3 weeks ago, or 3 months ago. Maybe something along these lines....?
Set GROUPBY=DATETAKEN PERIOD=DAY
Set GROUPBY=MODIFIED PERIOD=WEEK
Regards, AB