Group Workspace rows together to aggregate long-tail items

It'd be great to able to aggregate rows of a table into "All Others." For example, say I want to display only the top 5 individual values, then group everything else together and call it "All Others." There's probably a way to do this by creating some custom segments, but that's a bit of a pain and feels like overkill. I'd like to highlight a set of rows, right click, and "merge" or "aggregate" on the fly.