I'm always looking for good short green/alternative energy names. Most have been taken but there are still many good ones yet unregistered. The reason being the tech is still in the developmental stage.
Example..."EV" names. Many of these will be very valuable when we're all driving electrical vehicles. Or how about "H2" names....Hydrogen is the holy grail of our future energy fuel. The H2 names will one day have a prominent place in the domain world. I know that may be 10 or more years down the road but remember you can still register a name for 10 years for less than $100.