Johnny Jet says he can often play the "bumping game," which means you volunteer to get bumped off a full flight and even get paid for it. It's a nice way to extend your vacation. You can check to see if your flight is full online by pretending to make a reservation. Then when you get to the airport to check in, offer to volunteer to get bumped. You can even do it online if you're on Delta. You can get up to $400 for a domestic flight or up to $1300 for an international flight. Johnny says to hold out for cash (more likely an airline credit). You can also ask for an upgrade.
Johnny has also posted his 2013 year in review, where he flew 97 times for a total of 129,000 miles on 19 different carriers and visited 17 countries as well as 15 states.
Johnny recommends iExitApp.com, an app that will tell you what's at every exit when you're on a road trip!