One of the first places you could obtain Wi-Fi access in airports was in American Airlines's Admirals Club; now, it's free: The airline is still working with T-Mobile, but is providing this amenity at no cost to members of its Admirals [sic] Club and one-day pass guests. The frequent flyer membership number (for club members) or a unique PIN (for day pass guests) gets you in. Given that T-Mobile charges $20 to $40 per month for its HotSpot subscription or $10 for a day, the $300 to $450 annual club membership cost doesn't sound like a bad price if you don't otherwise need T-Mobile service or rely on other offerings.
It's a neat amenity, matched only by Continental, which had that nasty long-running battle at the FCC with Boston-Logan over their free service. Continental won.