My ‘z’ key has been (physically) broken for a while now. Generally this isn’t a problem because there aren’t that many places where I need to type a ‘z’ that I can’t autocomplete it. Between tab completion in the shell, and the irssi dictcomplete plugin, it hasn’t bothered me that much.
I finally got around to figuring out how to remap Caps lock to ‘z’, the magic lines to add to ~/.Xmodmap are
remove Lock = Caps_Lock keycode 66 = z
Most of the examples I found are for swapping capslock with control or escape(which are mostly obsolete now that you can use the Keyboard prefs thing in Gnome and swap keys around with a single click). Remapping caps lock to z is still too obscure to be in the nice GUI.
Now, if only two lines in a config file could fix the battery :-)