If you do the math, the break even cost on a hybrid is something like 10 years for most people, meaning that you'd have to own the car for 10 years with no major maintenance issues in order to just save the money you would have otherwise spent on gas. Going out and buying a new car may save at the pump some, but think about the fact that now you have car payments. Which is cheaper for you, an extra $10-$20 a tank? Or an extra $400-$500 a month for a car payment. So you're really not best off buying a hybrid because of gas prices.
There are a whole bunch of little maintenance things you can do to help improve the mileage on the vehicle you have already. They might not make a monumental difference, but things like making sure the air in your tires is the right pressure, you have a clean air filter, and your car is properly tuned can net you a few extra MPGs.
And if you really want to buy something new to save on gas, get a motorcycle. If you're not going for one that's brand freaking new, you can get a great price on one and they're cheaper to register and insure. My 2002 Honda Rebel cost me $3,000 to buy 3 years ago, $39 to register each year, and $200 for a whole year of insurance. And to top it off it gets about 80 miles to the gallon with a 2 gallon tank.