A great way to save money and help the environment is to ride a bike. 40% of all car trips made in the United States are under 2 miles, which could easily be done on a bike. Riding your bike is perfect exercise for your heart and a great way to stay in shape. It's also great for the environment, because it doesn't require any gas or electricity to get it going. Ridding your bike will bring you many benefits. You'll be stronger, look better and save a lot of money on gas.
Its very easy to install some bike bags, also called panniers, onto your bicycle. These will allow you to carry your laptop, briefcase, and a whole lot more if you go for the full front and back wheel system. You can also go old school and get one of the little “book shelf” racks for the back. While you are customizing your bike, I would also install some fenders to keep the occasional puddle from splashing up on you, and maybe a blinking light or two for dusk and dawn ridding. Your daily commute can turn into a very fun part of your day.
Two great commuting style bikes are Elektra Amsterdam and the Trek Lime. The Amsterdam is only around $500, has a chain guard to protect your clothing, a luggage rack in the rear, and a headlight in front that is powered by your pedaling. The Trek Lime is around $600, has automatic shifting and a seat trunk that locks. Mountain bikes are more rugged and heavier, whereas "road" bikes are easier to ride but more fragile and more expensive.