Without question, a Pivot Table is the fastest and most accurate way to produce a list of unique values in a field of data. And, when you base your Pivot Table on an Excel "Table" the list of unique values will update automatically when you "refresh" the Pivot Table.

Here is a link to a short video that I created that demonstrates SUMIF() and Pivot Table side-by-side:

http://www.thecompanyrocks.com/two-ways-to-produce-an-executive-summary-of-an-excel-list/

Danny Rocks
The Company Rocks