A bash-program that receives a photo and instructions about the desired text, and produces an e-card in Postscript, PDF, and JPEG: mk-greetingcard-from-photo.
The 2010 Christmas-card in my collection of Christmas-cards is an example of a card made with this program. The older ones were made manually using Gimp. Using this program to add the text has the advantage of getting more precisely located text; specifying each X-Y location as two numbers is more to my taste than the guesswork involved in using a drag-and-drop GUI method.