If you have yet to book your holiday travel way to cut it close! Never fear, United has extended its holiday fare sale to over 50 cities nationwide. Round-trip fares start from just $94 for bookings made by December 16, however you'll need to be flexible with your travel dates to secure the lowest fare. As an added incentive, United is also offering an e-certificate with the purchase of a 2009 holiday flight that can be applied to domestic flights in 2010. This e-certificate can save you as much as 50 percent off next years flight, but it is based on the number of holiday tickets you purchase in 2009 (the more you buy, the more you save).