We really love the idea of little individual leaves. We also think it could be a neat thing to keep from year to year for your child, letting invited attendees to birthday parties stamp their fingers to leave their mark on the day. Keep the same "tree" from year to year, just add to it as you go, alter colors if you wish, just make sure to date one or two so you know where it stops.
It's a great way to document all those who come see a newborn upon it's first few weeks of arrival. As family and friends pour into your home, have them stamp their finger to show their support for your little one. By the time their old enough to understand they'll have a lush, full tree, or even a forest! What a cool family heirloom.
We'll also take this time to note, that birds can be created from a single thumb print (just draw on the beak, eye and feet) and would also be cute on a telephone wire as wall art!