While "People who bought this also bought that" technology has been around for a long time, Booking.com has taken this basic idea and turned it up a few notches.
For example, while viewing a hotel in Barcelona, a little notification popped up that the most recent booking for this hotel was made at 16:07 by someone in France.
Is that the most interesting thing in the world? Maybe not, but it does show me that this hotel is at least popular enough to have received a booking recently from this website. Over the course of my session, many other messages might pop up. If you look in the "My Viewed Hotels" area, you will see a note under the Bellagio: "There are 23 people looking at this hotel." Other messages I've seen say things like "There is only one room left in this hotel," or "Someone just reserved a room in this hotel and there are only 2 left." These messages get your heart pumping and make you realize that if you don't act now you might not be able to stay in the hotel of your choice.
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