Anything that is homemade. Whatever it is. A drawing, wooden object, painting, flowers, meal, birthday cards made on Microsoft Paint, whatever. Gifts that have been bought at a store have no real value for me, while something the person has taken the time to make has a much higher value.
I never ask for gifts on any occasion anyway. If it's my birthday, my favourite gift is simply the presence of my friends. Hmm.. okay.. if we're at a bar, a beer or two is always appreciated..