They account for much of the $36 billion a year in revenue that airlines get from ancillary services—and an untold number of headaches (and heartaches) for passengers. We’re talking, of course, about airline fees, which include everything from advance seat-selection charges to blanket and pillow fees (we’re looking at you, US Airways and JetBlue) to Spirit’s dreaded carry-on bag fees, which now range from $25 to $100. What makes these charges all the more unpalatable is the difficulty of keeping track of them. Enter the good folks of Airfarewatchdog, the terrific fare-alert and travel-advice website. They’ve just updated their Comprehensive Airline Fees Guide and housed it on the site as a handy PDF file. Go ahead, download it. And don’t make us have to say “We warned you” next time you show up at airport.