Would it be possible to add an Excel style filter into headers of tables. It would work similar to the existing search box, but rather than being tied to a whole table it would be linked to individual columns, and rather than the user typing a value into the search box it would be a drop down list (or popup in mydbr terms) that contains all of the unique values in the respective column.
If you really wanted to push the boat out it could work exactly like Excel, where the user can select multiple entries from the list via check boxes, and the results would filter to only show the selected entries.