Here is a great place to search for artwork by theme, scripture citation, person, whatever: http://diglib.library.vanderbilt.edu/act-search.pl
The website description:
The Art in the Christian Tradition (ACT) database is a freely available, regularly updated visual image internet resource. Designed for scholars, students, pastors, and religious educators, all of the images may be used for educational and/or religious non-profit purposes. Images are added regularly. There are currently 4440 images in the collection.