What is the ruling on a mobile application programmer who is asked to create a photo library within a school program, another program to display a company's services, and a third for an Islamic charitable organization?

There is no harm in programming a library for permissible images on the phone, because photographic imaging is permissible out of necessity, according to the preponderant opinion. The fact that the man will use it for permissible matters makes it permissible for you to create it, and the sin of using it for unlawful purposes falls upon him, not on you. However, if it is highly probable that he intends it for an unlawful matter, then it is not permissible for you to make it for him, because anything that is used in an unlawful manner, or is highly suspected of being so, is forbidden to manufacture and sell.