Airline Fare Watchers

It seems like every major airline search site, such as Obitz, Expeida, and the like, all have some sort of fare water feature. I was just wondering how this has effected your travel planning process? Do you now try to plan trips far in advance so that you can wait for the lowest price? Or do you just watch ticket prices for a few days, see if the price goes down, and then order your ticket?

What other features would you like to see the travel website put out?