Since I tend to break my installation quite often while testing new stuff, I am always looking for more agile way of re-setting my system quicky. Of course backups could do the job, but I find a clean install much cleaner and safer for my purposes. So, here is a tip how to set keyboard layouts from the command line using GNOME. This is very useful if you speak more than one language:
gconftool-2 -R /desktop/gnome/peripherals/keyboard/kbdgconftool-2 --recursive-unset /desktop/gnome/peripherals/keyboard/kbdgconftool-2 -s /desktop/gnome/peripherals/keyboard/kbd/layouts -t list --list-type=string [us,de] gconftool-2 -s /desktop/gnome/peripherals/keyboard/kbd/options -t list --list-type=string ["grp grp:alt_shift_toggle,terminate terminate:ctrl_alt_bksp"]
Do notice: there are TABS in the empty spaces up there. GNOME's xml was intolerant for my attempts to replace them with spaces, and really only worked with the braces.