Gopher - Better hotel deals automatically, every time + cash back
FareUpThere - Earn rewards for your feedback on flights
Earny.co - Win prizes on Amazon purchases
Eighty App - Convenient travel wishlist app with booking alerts
HotelTonight Escape - The best getaway deals for tonight (or the weekend)
Skyscanner - Skyscanner.com compares over 1000 airlines to find you the cheapest airfares, fast.