I'm not sure if there's even a way to do this in excel, but I would like to insert into my worksheet a dropdown list from which a user can select multiple selections (either by holding ctrl or maybe checkboxes within the droplist).

In this list, they will be deciding which quarters to include in the report (ie Q1 2005, Q2 2005, Q3 2005, etc...). Is there a way to put these in a single drop list and allow users to select more than one?