A few weeks ago I was out of town for the weekend. I went to check-in online twenty four hours before my flight, and the airline gave me the option for a text message boarding pass. Moments later I received a text on my phone with my name, flight number, seat and a scanable bar code.
I carried on for my luggage so I was able to skip the check in counter completely. I went through security and to the gate with only my phone and ID and both were able to scan my phone.
This made my life so easy! No need to find a printer or wait in line to print out your boarding pass or worry about losing your paper boarding pass in your Mary Poppins carry on bag.