I have a column of names that get's updated daily. I would like to keep a tab
on unique names in the list on a daily basis. So if I look at the weekly
report, I would see how the headcount increased over time.

A few complications:
There are three worksheets. The first one is the list of names. The second
worksheet has the column that I referred to above, where users populate the
cells using a drop down list that gives them names from the list on the first
worksheet. The third worksheet is where I would like to report the trend of
unique names, in the column in worksheet 2, over a period of time.

Before I kill myself trying to figure this out, anyone has any suggestions?
Much thanks!