Today and tomorrow only, Frontier Airlines is taking 50% off select flights when you use coupon code DEC50 at checkout.
You will want to note that the select flights are only available for this discount if you fly December 1st through December 19th. If you are traveling between those dates though (or can make arrangements to travel during those dates) this would be a great way to save on your airfare this holiday season!
**Fine print: The 50% off only applies to flights to/from Albuquerque, NM; Austin, TX; Billings, MT; Bozeman, MT; Durango, CO; Kansas City, MO; Knoxville, TN; Mesa, AZ; Newport News, VA; Oklahoma City, OK; Palm Springs, CA; Provo, UT; or South Bend, IN.