I think the iPhone really solves the 'sitting at the airport with hours to kill' problem quite well. As iPhone owners, we know we can browse the web, catch up on email or the news, even check to see why your flight is late.
I have another suggestion. Give Adrenaline Golf Online [iTunes link] a try. It is one of the few games that really harnesses the power of 3GS graphics, but look quite good if you are on older hardware, and it works fine on an iPod touch too.
The game is basically miniature golf, with a pretty accurate physics engine. There are 72 courses in 3 different game modes. You can play online with golfers all over the world, or just play by your lonesome.
There are 4 different playing environments for 18 courses, which is how you get a total of 72. There is beach, forest, lava, and night. The animation and rendering of water and reflections is really stunning. The game play is challenging, and I easily blew an hour working through a couple of the courses.
All the courses have 3 difficulty levels, and have interesting challenges in getting your ball in the hole past a series of animated obstacles.
I'm not really a big game person, but I was instantly hooked by Adrenaline Golf. If I have any criticism it is that it is hard to predict how a particular hole will play and how far the ball will roll. Eventually I got the hang of it.
It might seem a little pricey at U.S. $4.99, but I think the effort involved in making this game was substantial, and I didn't mind the higher tariff.
If you're stuck at an airport or have time on your hands I suggest giving this game a try. I think it is especially good for people who like pool and miniature golf.
Here's a gallery of some screen shots: