You learn something new everyday. I was watching a show on the Fine Living Network called "The Top 20 Travel Tips" and the number two rule was to invoke rule 240 if you're ever in the unfortunate situation of experiencing a flight cancellation.
Rule 240 states that if the airline cancels a flight for a reason other than weather or an act of God, then they are required to put you on the very next flight to your destination regardless of the airline. So if Delta flight 1780 to Los Angeles is canceled and they can't get you out on the next flight until 8 hours later, but United has a flight leaving in two hours, then they must put you on that United flight - even if the only seat left on that flight is a first class seat.
You have to keep in mind, however, that the flight cancellation must be due the fault of the airline and not unavoidable circumstances. It might be a good idea to carry a copy of this rule with you whenever you travel just in case you find yourself in this position (and just remember that each airline has a different version of the rule, so print out a copy of your airline's version). Just remember that if you miss a connection due to weather, the airline will not honor the rule and you'll have to wait it out in the airport with everyone else.
Here's another great tip I learned when watching the aforementioned travel show: scan a copy of your travel documents and email them to yourself so that if, God forbid, you were to lose your passport or other identification, you have a better chance of more quickly resolving the problem and having new documents issued to you so you can return home as quickly as possible.