Environmental Impact

I'm reading this new book (as in, it was just published) called "No Impact Man: The Adventures of a Guilty Liberal Who Attempts to Save the Planet and the Discoveries He Makes About Himself and Our Way of Life in the Process".... but let's just call it No Impact Man, shall we.
Anyway, its gotten me thinking about my own environmental impact a lot more than I generally do. This dude, his wife, their 18 month old daughter, and their dog attempted to live in Manhattan for a year with zero environmental impact. I'm still kinda at the beginning of the book (page 67 of 243) so I don't know how it went totally. But still, I'm thinking about me more. I do things already like use cloth grocery bags etc, but I can definitely be more strict about the things I already do (ie if I forget my bags in the car, I'll go ahead and get the plastic ones). The way I'm eating now definitely decreases my trash output. Since I eat so much fresh I'm not generally using containers or packaging for my food (except meat...hmmm...).
I think my biggest trash offender is the cats. Their food cans are not, as far as I can tell, recyclable. They definitely have to have litter, and I scoop it into plastic grocery bags to throw out. I had the idea to use old litter bags (I mean, the bags and boxes that the new litter I've purchased was in) to scoop into, but then I can't recycle the packaging. Anyone got ideas about environmentally friendly cat care?
I get a lot of random mail I don't even look at too. The flyer thingies and all. I hear there's lists to put yourself on to stop getting those... I should do that.
I could definitely be walking places I'm currently driving to, though I do try to combine outtings so it's not quite as bad.
Shopping at second-hand stores as a first resort sounds pretty easy too. I already buy recycled and recyclable products when I can, and biodegradable ones where possible as well. I decided a while ago to stop using the dryer but that hasn't happened yet, heh. The aircon is a problem. Really, I'd suffocate without it. It just gets so hot here. And I rent so I can't really change it to something more economical or whatever. And I can't turn it off when I'm away, either, because of the cats. Huh, pets is kinda unenvironmental. At least, the way I'm doing it.
Anyway. I'm thinking about my environmental impact.