A close friend of mine, whose name shall remain anonymous for safety purposes, recently posted on a blog the following:
Do you want to read one of the silliest things to ever come out of a textbook?
...An existing adaptation may come under strong selective pressure for some new purpose, as did insect wings. These did not arise so that insects might fly, but rather as structures that were used to "row," and later skim, across the surface of the water. Later, the larger ones by chance proved useful for purposes of flight.
Insect wings happened to let insects fly... by chance? By lots of little evolutions over time? Insects just happened to have the right changes in the right places so that they could propel themselves through the air? I don't think so. I think natural selection is plausible in some ways, but not in this case.
Basically, evolution simply isn't logical. If professors and textbook authors can't see that, at least students can and, often times, do. Two thumbs up to my friend. Well done.