I recently took a vacation that required me to locate an airplane flight home. I utilized a number of travel sites like Expedia, Priceline, Orbitz and others, but had problems locating a flight I was satisfied with - that is the right combination of cost, time, length of layovers, and number of stops.
Well I used a fairly new website called hipmunk.com which pride's itself on being able to search by "pain tolerance" again the worst combination of the categories above - limit the hours you want to fly and much more. In utilizing this service I found the perfect flight.
Well they've already got an iPhone app and now have released an Android app. I highly suggest downloading this app and utlizing both the app and website next time you are looking to book a flight for business or pleasure.