Started an allotment (and blog, see www.waark.com)
Recycling both at home (with parents till I move into my flat may 1st) and the office (though for some reason everyone thinks the cleaners are responsible for this green move)
Cycling more and more
Maintaining my car myself - doing regular checks to maintain peak efficiency for my pocket and by preventing problems that hurt the enviroment too!
I'm also doing my best to arrange a slightly more rounded education to my scout group by teaching them the skills in foraging & bushcraft that help reduce their impact on enviroment. I also give them experience in gardening by making them sort out my allotment for me

I'm a regular on downsizer too.