Macro to have user select Criteria

I would like a drop down list or a User Input box so the user can select what criteria for certain periods. I can get the Autofilter to work in my Macro but I cannot figure out how to get the values in the Dropdown or Input Box to have the user select the custom criteria. Any help would be appreciated.

 Set rng1 = ActiveSheet.UsedRange

rng1.AutoFilter field:=4, Criteria1:=Array( _
        "20121104", "20121111", "20121118", "20121125"), Operator:= _
        xlFilterValues