These two urls came from this month's AllYou magazine:
matrix.itasoftware.com (powered by google) queries all airlines for the lowest fare during a month-long period. My parents are coming from STI to JFK in November and according to this site non-stop flights are available for much cheaper via American Airlines rather than my usual JetBlue.
Future Anny, take heed!
http://www.tingo.com/ takes advantage of hotel's "money back guarantees if the price drops between booking and arrival." The hotel is booked through their site and if the price drops it automatically cancels your old reservation and books you a new one.
Hotels are gonna love this little tool. /end sarcasm