#9 column header drop down of column values?

[Matt Stucky]

Add a dropdown box just below the column header title that lists all unique values for the column. when the user selects it, the data rows filter to just that value for the selected column.

is this even wanted? what about very large values? a column with 5000 values, for example, would be a very unwieldy dropdown. perhaps limit to columns where cardinality is below a certain value, maybe 100 or so.