One is to write articles online for eHow. They pay you for writing articles and after you've earned $10, they'll send you a payment through PayPal at the end of the month. The important thing is to write articles that people are going to be looking for. You also need to get a good foundation. The first month you might not make a huge hit but that payment goes up and up every month.
Have a yard sale. You probably have a ton of things around your house that you could be making decent money off of. Whether it's old toys that your kids don't play with anymore or a brand new computer that has a broken part, people will be willing to buy. Even if you don't make a ton of money, you'll still be cleaning your house, garage, basement and attic out.
Another helpful hint is to save your change. Usually after you go shopping or even after getting a coffee, you end up with a pocket full of change. Place an empty jelly jar on your bureau and every night when you're getting undressed, empty your change into the jar. After a few months, roll the coins and then trade them in for cash at the bank. If you don't want a ton of change, use it when you buy something. Cashiers like change so they don't have to open a roll of coins.
Combine all your errands into one trip to save gas. This not only helps because you're not driving as much, but because you use more gas when your car is cold. When you combine your trips, it stays warm. You don't have to take your car to the shop as much either. Also ride with friends to work. Ride in their car one day and in yours the next. You save mileage on both of your cars, you save time between services and you save gas.