Pros: uses biodegradable materials, recyclable
I got an ATP EarthDrive for Christmas. I think it's a pretty cool product. You can get a 1-8 GB flash drive made of eco-friendly materials (i.e. corn-based plastics). ATP also plants trees for every EcoDrive sold as part of the EarthDrive project. The EarthDrive itself is also waterproof, shock proof, dust proof, and electro-static dischage proof. So it's a tough little bugger.
It's definitely a bit on the expensive side. You can find a standard 8 GB flash drive for aounr $20-30, whereas the EarthDrive version costs about $40. But if you're willing to pay a little bit of a premium for the low environmental impact, the EarthDrive is a cool product. As far as I can tell so far, it works just as well as standard flash drives.