A real downside to hooking alice up to my monitor, so that I can show a co-worker something on a screen size much more readable than 10.1″ @ 1024×600, is remembering to use her keyboard instead of my workstations!
Now of course when you consider that my workstations keyboard is like in front of a 20″ @ 1600×1200 monitor, it is rather easy to have a head popping moment!