To cut costs after the economic crash of 2008, the airlines cut back substantially on flights. Now that traffic is returning to prerecession levels, planes are more crowded than ever. The result: a surcharge on traveling on the most heavily traveled days. American led the way in September 2009 by adding a $10 fee on dates around Thanksgiving and New Year's. Within a few weeks, US Airways, Delta, Continental and United added surcharges around Christmas, spring break, Easter and Memorial Day. Now most airlines have surcharges of up to $30 on nearly any flight this summer. (You can find a complete, unsettling list of peak-travel surcharges by airline at farecompare.com.) Look out, Arbor Day you could be next.