Using Unique Values in as a combobox value list
 

I am trying to see if this is possible. I know it is in Access but I'm not
sure it is in Excel. I have a few coulmns with repeated values and I want to
find a way to get the unique values from these coulmns and use them as the
values in a combobox list. So there are two steps to this, first is defining
what the unique values are and then using those values in a dropdown control.
Thanks for the help.