Metasearch and its evolution
Let's face it, metasearch in its current state is somewhat like the web of 10 years ago. A list of plenty of choices some of which aren't event entirely correct (comparing different room types for example). Trivago knows it, Momondo knows it, even Kayak knows it, and going through TripAdvisor's earnings call notes it's pretty clear they know it too. Both Momondo and Trivago believe the future is in personalization. I think that's a great idea, it'll take a lot of data to get there though.