I have a 2 year old aluminum (not uni-body) 15" Macbook Pro. Today when I turned on my computer, the front light went on, I heard the hard drive spin but the screeen remains completely black. Any tips on how to get my computer working again?
Do you know if you have the NVidia GeForce 8600M GT graphics card? If yes, it's almost definitely that. Check this support document. Take it to an Apple Store. You'll get a free repair.
Another thing to try would be to reset the SMC http://support.apple.com/kb/ht3964
Sometimes the Mac can get confused about whether it is running an external display (clamshell mode) or not. If that is the problem, resetting the SMC will fix it.
But the other suggestions on here are also very valid.