People associate being frugal with being green, but that not necessarily true. You can also be frugal in a way that's not very environmentally friendly. I'm just going to focus on the green frugal ways that I'm going both though. I believe you will more bang for your buck and feel better about yourself if you can do both.
1.) When gas went high, a co-worker and I started to car pool. Now since the price of gasoline has gone down, driving alone would be nice again. But, since we both realize the value to the environment, we are continuing to car-pool.
2.) Instead of using trash can's for our smaller waste baskets, we use plastic grocery bags. I also line a used kitty litter bucket with 2 plastic bags (one inside of the other bag), and put the cat refuse in the bucket and put the top on.
This save my trash bages, and I get additional usage out of the grocery store bages I use.
3.) I like to extend the life of my appliances and machines as much as possible. My lawnmower handle has been welded 3 times, and I even use tape to hold it in place in some spots. My snowblower is over 20 years old. I just fixed my dryer, the felt liner at the top was wore to the metal. I do my car maintenace myself: change line, change brake shoes pade.
4.) I save the junk mail envelopes and use them to write throwaway notes on. Not a big savings, but still good...