A few years ago Julieanne Kost published Window Seat, a collection of images taken on regular commercial flights, enhanced with Photoshop.
I liked the idea, and thanks to the relative unobtrusiveness of smartphone cameras have built up a library of my own in-flight photos. I have to admit I'm not quite sure what to do with it, cloud and sky now occupying several hundred megabytes on an external hard drive.
I added quite a few more to the collection when on holiday last week. I try to use flights for some concentrated reading, but am forever distracted by the extraordinary vistas and horizons passing by.