CapsLock has a perfect reuse as language switch for those who use a second language (which is most of the world). It is much easier than Alt+Shift/Cmd+Space, and it will indicate another input language with the LED even when tray/menu are not visible.
Meh. In Linux, at least, you can do this:
setxkbmap -option grp:switch,grp:shifts_toggle,grp_led:caps us,se
It will toggle between US and Swedish layout when both shift keys are pressed together (basically the only time I use rshift), as well as toggle the caps led on when the Swedish layout is activated. I have caps lock bound to ESC, for more convenient for vim usage.
Please leave CapsLock alone.