I'd like to count the occurrence of unique items found in one column of about 120 items. I can't find a way to do this in Numbers.app
Here is a clever solution posted in an apple discussions thread.
You basically create another column, and use the formula
=IF(COUNTIF(A$1:A1, A2)=0,1,""). This will display a one for the first occurrence of each unique item. You then simply sum the whole column and you get your count.