For instance, to make a reservation by phone Southwest charges nothing, while US airways adds a fee between $25 and $35.
Unaccompanied minors are charged a $25 fee on Go Airlines and $100 on Delta.
If you have a confirmed seat and want to fly standby on another flight instead, United charges nothing for that option, Jet Blue will ding you $40.
Here's the link where you can try it out for yourself. When booking for a family you could easily save a couple hundred bucks by keeping track of these types of fees.
