Potlatch gets fewer new features in a year than iD does in a day, but occasionally something creeps through.
This week/month/year, that’s the ability to add a function key shortcut (F1-F4) to a relation. Open the relation dropdown menu in the advanced relation panel, choose “Assign to F1” (or whatever), and from then on, you can add the current selection to that relation by pressing the key. It’s particularly useful when building route relations.
Function keys can, of course, also be used for memorising tag combinations and for switching between background layers.