Green programming – contribution to the environment

Everybody seems to be talking about a green and environment-friendly job. Well I wondered how we, as IT guys can contribute to this phenomenon and came up with these answers (after a bit of research).
In our workspace we can do these things:

• Write correct and OO code, to save seconds of processing time
  If you save 3 seconds in a code and this gets executed 1000 times a day for 1 month (30 days) you’ll get a total time of 3*1000*30 = 90000 seconds = 1,1 day per month of execution time saved.
  That’s a huge difference isn’t it? And that’s only what 3 seconds does….
• Don’t print out everything but use digital copies. Share books, instead of buying two or more copies.
• Use servers that are hosted in green data centers (more info)
• Live close to your work and use public transport (if possible), ride a bike or walk.
• Be sure to shut down air-conditioning and heating at night.
• Switch off you system and monitors.
• And the best one: try to work as less as possible.