I'm going to pass on doing the Challenge, but I've got one idea to share. Please excuse me if someone already came up with this one.
When you fill up your car with gas, let it stop automatically (you're not supposed to top it off anymore, which I totally don't understand but it has something to do with Al Gore
). Round off the amount of your bill to the next highest dollar and put that money in your savings. Kind of like the "keep the change" account at everyone's favorite bank.
Good luck to all!