I'm sure there must be a way of doing this ...

I have 2 columns of data, with around 2,000 entries in each.

Items in Column A tend to be one from a list of c 10 different variables,
whereas Column B contains maybe 300 variables.

I need to produce a simple list that shows when Column A = "x", what the
possibilities are in Column B. This is easy to achieve using Auto Filter -
just filter Column A and then the drop-down list on B shows the various
possibilities. But how can I get this to show on the worksheet somewhere?
Obviously I can sort by A then by B but this then produces many rows of
data - all I want is a 'summary' list.

Thanks.