Traveling, and like to use the internet while you are waiting? Check to see if Boingo offers service at the airport, and then look to see if that location is offering the American Express free 20 minute offer. I found it today and it was great to be able to check things quickly without having to pay.
On the page I saw, it was located down near the bottom of the Boingo log-in page. Be sure to check before you pay!
Note: I've now tried this in a few airports. It seems like it is a location by location type of deal. Still good to check, but be aware that if you can't find it, it is probably because it isn't offered.