Here's an article about a flight tool http://www.yapta.com/ that appears potentially very productive.
Highlights of the article;
1) Service sends you an alert when your purchased airline ticket goes down in price either within the no penalty 24 hour period (or in the fare lock range you've purchased from airline - sometimes up to seven days) or should the price decline more than the change penalty.
2) Service is free to individual consumers (savings split for corporations)
3) One company that used it and saved money, stated that 90% of their savings were from the first 24 hour changes
4) Yapta also offers service for hotels - but currently only for corporations
worth a look