Maybe ask a local place for a quote on fixing it--whether that means a new bulb or something else. I've never heard of anyone actually doing that, but then I've seldom heard of a backlight failing in the first place.
Otherwise, maybe take the back off and see if sunlight through the back does any good? 🙂 I know the Apple logo on a PowerBook can sometimes let enough sunlight through to see the screen with the bulb turned off. Just don't do mess with it while plugged in--could be a shock hazard.