I've been using Atom feeds to publish announcements to my course websites recently. The ‘please check this page daily for changes’ directives I saw on a few other pages were too painful to bear ;). I've written a little PHP script to convert the atom.xml into XHTML so non-atom students can still read the announcements online, and I've been using rss2email in a cron job and a procmail rule to automatically email the class any new announcements I post in the feed. It works rather well I think, even if noone ends up actually looking at the feed ;).
atomgen -o atom.xml new --title 'Physics 201' --author 'W. Trevor King' \ http://www.physics.drexel.edu/~wking/phys201 echo "Changes to the Phys201 website will be noted in this feed." | \ atomgen -o atom.xml add -i atom.xml 'Feed purpose' \ http://www.physics.drexel.edu/~wking/phys201