After Dec. 15, holiday airfares can double — and triple — in price. So right now is a great time to redeem frequent flier miles. Collect a cool 1,000 miles on United Airlines in less than a minute with Bckstgr. Get 400 miles with sign up and an additional 200 miles each for linking to personal Facebook, Foursquare, and Twitter accounts. Best of all, the miles post instantly to a United account, a process which usually takes several months. This is also a great way to keep your miles from expiring due to inactivity. If you’re not a frequent flier, still sign up and earn enough points through the promotion for a free magazine subscription, restaurant.com vouchers, and more.