You can use travel search/aggregator sites to reduce the number of sites you actually have to visit yourself. Most travel search sites work by checking fares in real time from a host of different sites around the web including sites likes Orbitz, OneTravel, etc. along with many of the direct airline websites. Here are a few you can try:

PriceGrabber.com Travel *full disclosure: this is who I work for
Sidestep
Mobissimo
Kayak

Each site is setup differently so you'll need to find one that works best for you, but no matter what, you will be able to save a great deal of time in your travel search.