Word of Mouse: Yapta

Here’s how to stretch your travel dollars. I wanted to try this site out before I recommended it to you. It’s Yapta.com.
Book your flight with Yapta and they will monitor the fares and alert you if and when they drop. They also arrange for your refund with either an airline credit or voucher. I tried it for a nonstop flight that I needed to book early and within a week I received a $108.00 refund because the fare had dropped. Your refund is in the form of an airline voucher or travel credit. I advise taking the travel credit. The entire $108.00 credit can be applied to a future flight whereas travel vouchers typically don't retain any residual value. For example, if you have an $80 voucher and only use $50 of it, you will lose the remaining $30.

http://yapta.com