You enter your starting and destination cities and your travel dates, and in very short order up pops a table listing all the flights for all airlines.
Each row of the table is a flight, and the flights are ordered by price from least expensive up.
Each flight is shown in a compact but highly informative way, a single color-striped bar showing you at a glance when it departs, where you lay over, and when you arrive. Clicking the bar opens a pop-up with full details. In the popup is a "buy now" button that sends you to one of the standard travel sites, such as Orbitz, to complete the purchase. There's also provision for round-trip scheduling, so naturally designed there's no need to explain it.
Great site. Book your trip to the Final Four now! If that link gives only the basic search page, get fresh results by entering from: SFO; to: IND; depart: 04/01/2011 (that's a Friday, enter 04/02 if you can't leave until Saturday, missing attractions like the high-school All American game); return: 04/06/2011.