Anyone who has flown in recent years has surely noticed that nearly every aspect of traveling now has a cost: checking a bag and enjoying an in-flight meal or even a soda comes with a price tag. Though largely regarded as a pain by thrifty travelers, such fees have been saving grace for many major airlines. A new study reveals that airlines have almost doubled the revenue they receive from ancillary fees like baggage and in-flight food charges over the past three years. In 2010, 47 airlines raked in $21.5 billion in extra fees, that's an increase of 96 percent from what they brought in with the charges in 2008. In the case of some smaller airlines, such charges now make up a majority of their yearly revenue. The review, conducted by research company Idea Works, notes that "the oil price peak of 2008 caused huge losses and prompted US airlines to start charging travelers for checked baggage." With oil prices back on the rise, and airlines happily benefiting from the fees, it looks like travelers will continue to long for the days of all-inclusive plane tickets.