Fare Finder Software
 

I am looking for a website or software that will notify me when the airfare for a specific route is reached. I would like to able to select a date and route, then put in a price I would like to be notified if it is reached. Preferably the app would search several times per day for my route and price and if it finds it, it will notify me. It seems like I have seen one before, but I can't find it now.
Thanks in advance for the help :D