Hipmunk is a travel start-up much like Travelocity or Kayak, however it focuses much more on data visualization. From the get-go, users are introduced to a large, simple interface. After inputting details on your trip, you get to see your results in a colorful, organized timeline that allows you to visualize a lot if data at once. I would say this differs from the many travel sites that give you text-based results.
Hipmunk allows for a lot of options while remaining visually appealing. Not only can you sort by different options such as prince, duration, arrival, but you can narrow your search down to specific airlines, start a parallel search on the same page, and talk to live help, if available.
Aside from the functionality of the site, there are several principles that help this succeed. For one, the obvious use of a grid helps align this information to give users a better sense of the timeline. The menu is also well done and simplified, where drop downs are for secondary functions that might not be used right away. Certain data is also noticeably clickable (buttons) as they give the affordance of being pushed.
Overall, I would just say that Hipmunk, Inc. did a notable job in displaying such a large amount of information in a very simple matter. Compared to other travel sites, it really does succeed in helping users visualize, however, it goes without saying that there is always room for improvement. In fact, I discovered later that Sacha Grief had several ideas on this: Hipmunk Redesign