I teach a regional overview course where each student does substantial research on a separate culture within that region. They give weekly reports on their research, and at the end of the semester, they write a term paper. For many of them, this paper is just their weekly reports put together. They have the option, though, of writing a short story set in their culture. The story must show mastery of the archaeological record, and give the reader a good idea of what daily life was like at that time and place.
This semester, about half of my students chose the fiction option, and their papers were fun to read. They ran the gamut from fictionalized accounts of documented archaeological events, to science-fiction stories involving time travel, to magical realism involving an invader and his pet mouse.
I really like this assignment because it represents the best of the liberal arts: forging links between scientific and humanistic disciplines, fostering creativity, and encouraging self-expression. If you're interested in doing something similar, I have two recommendations:
1) make sure students know they will be graded on the academic content of their story, not (or not solely) on plot, character development, etc. Make them include footnotes or an annotated bibliography for their sources.
2) include a significant amount of traditional academic writing/research in the class, in addition to the fiction component. This activity works for my class because my students have done a huge amount of research and writing on their culture before they turn to fiction. By the time they get to the final project, they've written nine short (1-3 page) papers on their culture's subsistence system, architecture, mortuary customs, etc., etc. In other words, we can have fun with a fictional account of their culture because they've proven without a doubt that they've mastered the material.