PointsHound is a hotel booking website that allows you to earn frequent flier miles for all of your bookings. I have written a piece about this service that you can access here (note that the 100 mile sign up offer is no longer valid).
Now, you can also earn American Airlines AAdvantage miles or Virgin American Elevate points in addition to existing partners of United, Delta, Hawaiian, Etihad and Air Baltic.
If you are booking a non-chain hotel and would otherwise use a site such as Booking.com, it may make sense to have a look at what PointsHound has to offer. There is a similar service called RocketMiles (you can read my take on RocketMiles here).
Note that if you sign up for either PointsHound or RocketMiles using the links on LoyaltyLobby, we may get a referral credit.