One of the little tools I really learned to love is synergy. It allows one to share one physical keyboard and mouse across several machines, so you can just move your mouse cursor to the edge of your display (or set up a keybinding by your choice) and magically your mouse enters the other screen. It's also supposed to work across Windows and Mac. However, using mainly two linux machines running X11 and xmonad, one day it stopped working like a charm and on the client (the computer you want to control remotely) I only had an US keyboard layout, and frustrated by some hours of unsuccessful googling I stopped using synergy at all.
But to my delight I just stumbled about an user having the same problem and a solution and running setxkbmap de before starting the client solves my problem. Yay! I hope I don't get too much bad karma for all the hatred I accumulated while trying to fix this problem.