I have a form that a user inputs different categories using drop down boxes.
I need to be able to summarize that data. Is there anyway to get the single
value from the list. For example, someone could choose the same category
twice, but I only want it to be pulled into my list once. I'm not sure if I
need a match or index or if there are any formulas specific for this kind of
question.

EX)
Categories
Pillows
Pillows
Sheets
Tablecloth
Pillows

I would like to lookup off of the above entries and create a list that would
read

Pillows
Sheets
Tableclothes

Thanks