A folding bluetooth keyboard-trackpad combo has been a lifesaver for me! Any time I need to work on something in desktop mode it's saved a lot of time and frustration.
I usually just use the built in track pad and the digital keyboard (or whatever you call it) but sometimes is it easier to just type with a normal keyboard if I have to change a lot of config files (I use a USB hub and keyboard then).
But I only mod my games in desktop mode so maybe that is why I don't see the need of a true dedicated keyboard and mouse set up?