yeah, electricshoe, that's a great idea. Great way to get unique content. But asking my students to write unique content would result in a a lot of duplicate content. See they like to cut and paste. I love getting papers in from the students with English far beyond their capabilities. How to spot plagiarism? Ask them what it means.
Here's an idea I did have: I write term papers for people I know back in the states on occasion. It's a lot of heavy duty unique content. If someone collected all of the student term papers, they'd have a hella bunch of unique content to put up on a site.