LOL I just did the same thing not knowing thread was 3 years old.Wow I'm responding to a thread that ended last year. In any even I'm bored and felt like making this post anyway. I was lucky enough to get the following .co domains
Biofuels.co
Cloudcomputing.co
CloudTechnology.co
CleanEnergy.co
FuelCells.co
NatGas.co
and about 100 more. I just listed them at ShowcaseManager.com
Eric