Today's Tip is: Yapta.com
Yapta is a site partnered with Kayak.com that tracks the price of flights.
You enter the information of a flight you are considering flying and it will sent email updates when there are changes in the price of the flight, particularly when the price goes down.
OR
If you already booked your flight you can enter the flight info and the price you paid and the site will email you when the price goes down and how (and if) you can get a refund or credit with the airline.
I've personally used this to save $50 on a flight to Las Vegas, I used that credit to help pay for my flights to Los Angeles earlier this year when I went to Disneyland.