Talk about your green-friendly mashup - mybabytree.org lets you can sponsor a tree planting through WWF (World Wildlife Fund) - and then lets you see the exact area of forest your tree is growing in, thanks to Google Earth.
Trees cost $US5.50 (about $6) each to sponsor via PayPal. The trees are being planted in Indonesia as part of a venture by WWF. Once your payment is processed, you get an email informing you that your tree will be planted in a 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."
The Ecogeek blog pointed out that while the resolution in Google Earth isn't quite good enough to be able to make our your particular tree, "even now the context is nice". This idea is geeky, I like. :)