I've just wrapped up a course for my Master's Program (through Lamar University-in Education, Digital Leading and Learning) on Digital Citizenship. It has been a very interesting and important topic to spend time on. We have spent time considering Mike Ribble's nine elements of digital citizenship and I appreciate the way he breaks down this very daunting topic into tangible issues that our students and our schools are facing daily. It has provided a framework for my thinking and how it is possible to implement digital citizenship for K-12 students.
The one thing I found very interesting and the most useful about digital citizenship was surprisingly copyright, fair use, and Creative Commons licensing.