Passengers have become accustomed to additional airline fees. The modern traveler doesn't blink an eye at a $25 checked-baggage fee, or an $8 in-flight snack pack replacing an in-flight meal. But will we be willing to pay a fee to check-in with an airline employee? Or to hold an infant?

George Hobica, founder of airfarewatchdog.com predicts higher fuel costs could lead to more airline fees this year. The model works: U.S. airlines collected more than $6 billion from such fees in the first nine months of 2010, according to federal statistics.

Hobica created a list of potential fees U.S. airlines could implement in 2011. While some may seem far-fetched, Hobica says some of the fees have already been imposed in the U.S. or Europe.

So what fee do you think air passengers are mostly likely to pay?