I make my capslock a backspace. Seriously, when do you really need to type so many capitals that can't just be rationalised by using Shift instead? Using it as Control as well is a great idea! You should first try out Autohotkey, instead of resorting to registry hacks.
Cheers
Ah, remapping it to backspace is kind of interesting. The reason remapping it to control works well for me is that most of the keyboard shortcuts I use for things (and I use a lot) use it, so remapping the capslock key to it helps you keep your hand on the home row more.
