TechCrunch reports on FlySpy, a site that will help people buy the lowest priced airplane ticket for a given destination:
The way it works is that I give it a departure city and a destination city and optionally a departure date and length of stay. The search result, which returns very quickly, will present me with a graph of flight prices over the next 30 days so that I can quickly look at which days are the cheapest to fly. To book a flight I just click on the point in the graph. Simple.
That's a pretty useful UI innovation (especially if you're able to drill down into individual days to find the lowest fare on that day), but it doesn't help you much if your travel dates are inflexible. The killer airline reservation app that I've been wanting for several years would tell you when to buy your ticket for a particular flight. Airlines update their fares several times a day and hundreds of times over the course of a month. Depending on when you buy, it might cost you $250 or $620 for the same exact ticket.
What this hypothetical app would do is track fare histories and then release forecasts based on those histories. If you want a RT to SFO from JFK on 4/12/06 returning 4/17/06, the site would tell you to buy your ticket three weeks out or when the price hits $298, whichever comes first, but to never wait until the week before, when similar flights begin to sell out.
A thornier problem than the one FlySpy addresses, but it could save people a lot of money. (This would work for hotels and rental cars as well probably, although I don't think their prices fluctuate as much.)