Southwest threw the first punch in this round, lowering prices to a ridiculous $25 a seat in their football-themed "4th Quarter Sale." If you're flying distances under 374 miles -- like, say from Los Angeles to Las Vegas or Los Angeles to San Francisco -- it's really only $25 each way. Prices go up in mile increments, so it's $50 from Los Angeles to Reno, $75 to Salt Lake City, and then $100 to New Orleans or Chicago.

American Airlines came out fighting, offering up its own $25 flights on the same routes as Southwest. The AA sale isn't quite as organized as Southwest's, and you'll have hunt and peck to figure out where the deals are. Your best bet? Find a route you like on Southwest, then click to AA to see if they beat the ticket. You should hurry to take advantage of the final months of travel sales ... 2009 was the year of the deal, but 2010 doesn't hold the same promise.