Colleagues, I received an excellent list of data sources from a representative of the Council of Professional Associations on Federal Statistics (COPAFS), at the Midwest Political Science Association meeting last month. This list contains links to federal data sets on a very wide range of topics. You and your students may find this very useful.
The list is in a PDF document here. COPAFS's website is www.copafs.org. Let me know if you find this helpful.