get one of the little USB lights (just plugs into the USB and has a flex-neck) very handy for dark rooms (not as techy looking as a back-lit, or is it?)
What kind of iMac? I ask because mine is a G3 iMac, and I've used one of those USB lights, and while it illumines the keyboard very well, it shines off the screen, which is annoying in a dark room.
Here is a review of a glowing keyboard called the EluminX; according to the review, it's good, but it's not perfect, and it's a PC keyboard, whic means Alt=Cmd and Windows=Option.
I bet backlit keyboards for consumers will grow in popularity over the next several months, and we'll eventually see Mac-specific models