Really sorry to be the bearer of bad news, but I always feel it's best to be honest. I don't know if there is anything that can be done to improve the damage cosmetically, but it doesn't cost anything to make an appointment at the genius bar and see if there is anything they can do. I know that they have been able to adjust hinges and latches for people, and possibly they could straighten out the ding a bit. No way to know since we haven't seen it.
Fortunately, your Mac still seems to work without issue, which is good. It may be that the damaged corner absorbed the force of the blow and the damage is cosmetic rather than functional. It would have been far worse if the Mac had quit working after the fall.
You were probably hoping to be told that Apple would fix it for free under warranty, but unfortunately, accidental damage is not covered--only defects in parts and workmanship. It would be no kindness to give you false or misleading information.
Really sorry about what happened to your Mac and that I could not give you any good news. It was very kind of you to give me a star anyway, and I thank you for it. It reflects good character and generosity on your part. This will serve you well in life.
One thing you can think about--the possibility of fixing it yourself some time in the future when you do have a bit of extra cash. You can find step by step instructions for fixing your Mac at ifixit and PowerBook Medic and elsewhere. Parts are available there and on EBay if you know what you're looking for. Sometimes you can even find stuff at a local AASP. Our local AASP, Dot Foil, has several parts machines on hand, and has been very generous with hard-to-find iBook feet and screws. If I needed something like a case, I would probably ask there first and see if they happened to have one I could purchase from a parts machine. So often, it's the internal parts that get used, leaving the outer case to be recycled. Just some food for thought.
Good luck to you, and happy computing!
