To start with, I've become almost militant about using every last drop of products like toothpaste, shampoo, and face wash! I've found that I can squeeze a toothpaste tube so much that it lasts almost a month past the point where it looks like it should be thrown away, and if I store my shampoo bottle upside down it seems like I can get an almost never-ending supply out of it (of course, I have very little hair to wash!).
Since I eat simple meals, I can pretty much survive by using the same bowl over and over (yes, I rinse it out thoroughly), along with just a few other utensils, a glass, and a coffee mug. I'll use this minimal set of dishes all week long, then switch to a second set, and then use my dishwasher once every two weeks to start the cycle over again. Needless to say, it takes me forever to go through a box of detergent! Similarly, I only do one load of laundry each week (by reusing my towel and wearing my pants multiple times), which saves me so much time.
My weirdest miserly habit began when I started to get in shape and actually enjoy sweating a little bit. Since most of my trips in the car are pretty short (15-20 minutes), I almost never use the air conditioner anymore! Seriously, I don't think I've turned on my car A/C in over a year (unless I have a passenger)! Actually, everywhere I have to be (like my office, shopping malls, or movie theaters) seems extremely over air conditioned to me, so when I get into my warm car it feels absolutely great! I always roll down my window and my sunroof to get a good breeze going, and if I sweat a little bit, I just figure it keeps my body healthy! I've even kept up this habit through Austin's hot summers - it just doesn't bother me anymore. I think this habit has also contributed to the long running life of my 1998 car, too!