Even better, be witty in your writing, be creative, and steal his heart with your wits. You could find out funny birthday one liners, and put them on paper.
Dedicate it to him, and capture that look on his face while he sees you making a complete idiot of yourself (oops, that might happen if you don't know how to sing). Something like Hilary Swank does in P.S. I Love You. Well, why not call him on the stage and sing along?
These items could range from a pen to a shower gel, an electric razor to a pair of socks... anything that might come handy to him! Well, this gift really depends upon how much you know him and his needs.