Your $5.50 donation will buy a tree, lifelong care and feeding, scientific study of the forest that it becomes a part of, and the exact coordinates of where that tree is on our big beautiful Earth. Linking that data with Google Earth shows the precise location (on the island of Borneo) of the tree, as well as all of its hundreds of neighbors.
Unfortunately, the resolution of that corner of the the Earth is going to have to be increased significantly before you can actually see your tree, but even now the context is nice.
You can buy trees that will be planted in Indonesia today at MyBabyTree.org. Think link provided takes you past the annoyingly long intro and straight into the site. PayPal integration makes the whole thing a breeze. I planted 2 of them myself (USD$11) and received the following message in my inbox:
Your baby tree will be planted in the next few days. Once that is done, we will mail you the exact location and you will be able to see your tree on Google Earth.
Hopefully they mean e-mail...and not paper mail...because that would be annoying.