Their best airfares are often similar to Farechase as well, they just don't always match Kayak.
Sidestep
A few points about Sidestep -
- toolbar option
- lots of travel deals listed on a separate page
- similar breakdown of fares to Farechase including time of day
- straightforward setup for one way or return airfares
- flights originating outside of the U.S. are priced in USD