I recently purchased a backlit keyboard and am typing on it right now :happy:.
I'm using a Saitek Eclipse II keyboard. I bought it because it scored high ratings everywhere on the Internet, and it's relatively cheap. I use it as an external keyboard for my laptop. It's full sized, has basic multimedia controls, and there's a choice of three backlight colours (blue, red or purple) which you can change by pressing a button, or turn off. There's also a dimmer switch for the backlight. The keys are very responsive, soft and quite, and have good tactile feedback. It comes with a detachable, adjustable wrist rest.
Cost me only £23.49 in the UK from overclockers.co.uk. A US froogle search shows you can get for as cheap as $43. There's also the earlier 'Saitek Eclipse' version which looks different, and only has a blue backlight, but is cheaper than the newer version.