The obvious one is …
Work from home.
In one fell swoop, you reduce the impact on the transport system, remove the duplication of building works like highrise office buildings and cube farms, and reduce the electricity impact, by using your windows to make environmentally friendly light and air conditioning.
There are other indirect benefits – by working in your local area, you will keep your local area alive, by buying lunch locally, and buying your coffee from the local shop (hi Bubba 🙂 ).
The second, is to work on or support the use of open source software.
Closed source is based on restricting access to software, which inevitably leads to pointless, non-innovative duplication of efforts. I’m not talking about the duplication of competitive features, or key differentiators that make your business a success either. There are a myriad of tiny internal tools written in every company or project, to just get stuff done, which if shared could improve your bottom line, just by sharing the code amongst all the other companies in the world that do a similar thing.
Do something for the environment today. Share.