Above: A subject's eye-movements are tracked while testing the Kayak.com redesign.

How big of a deal is a site redesign, really? For travel-booking heavy Kayak, it’s everything. That’s why it took the company six months, one $30,000 eye-tracking device, and countless A/B tests to perfect its new website look, which is being unveiled today.

The eight-year-old flight-, hotel-, and car-reservation company recently released a new iPhone and iPad app. Inspired by the minimalist user interface of the iOS app, Kayak decided to give its website a similar pared-down look aimed at helping customers find what they’re looking for more quickly.

Online travel is projected to be a $313 billion industry in 2012, and while Kayak and other major players have voiced concern about Google’s recent foray into flight search, the relationship is more tangled than it appears on the surface. Google’s competing flight search feature is powered by ITA, a company it bought in last year. ITA still provides U.S. fight search results to Kayak, which happens to power Bing’s travel search results. (And not that they’re hanging out in the same travel-industry bars or anything, but ITA and Kayak headquarters are a 35 minute drive apart.)

Kayak co-founder and CTO Paul English told VentureBeat he’s not threatened by Google’s flight-booking tool. “Its first flight product was pretty geeky. It was a nice layout but it was focused on a technical audience.” English also said consumers aren’t yet comfortable using Google directly as an e-commerce engine, as they are with sites like Amazon. “They don’t think of it as a place to shop or buy, and travel is an important enough purchase for people that they want a site they trust.”

To hone its new site design, Kayak brought test users into its lab in Concord, Mass. The subjects were told to complete a task, such as finding a hotel or flight, while 10 to 12 engineers observed the process in an adjoining room. The engineers tracked where the subjects looked using an eye-tracking tool. By observing shopper’s facial movements and where they clicked, Kayak was able to remove distracting clutter and simplify the site layout.

Gone is the black bar across the top of the page, affectionately referred to as the “unibrow” by Kayak employees. Advanced features such as searching by code-share flights or long layovers are still available, but they’re hidden by default since the majority of visitors are mere “amateur” travel bookers. Automatic resizing has also been improved to accommodate increasingly larger screen sizes.

Kayak thinks the new design will increase conversion rates. The company will continue to tweak the look and feel of Kayak.com after today’s launch.

Here are some screens of the new, very iPad-esque site, as well as a screenshot of the very first Kayak.com design: