In my experience in nanotechnology, green technologies and/or clean tech are the new buzzwords for VC's. I would be really interested in leveraging web applications for this up and coming industry. One great application might be a way to use the web for carbon credits. You bid on carbon credits, real-time. Think EBay goes green.
Another more cynical side of me thinks that this is "green-washing". Big companies want to appear friendly to the environment, when they really aren't.