This block by Michael de Raadt provides students quick insight into the timezone that their course deadlines are set to (and calls out the difference to their own timezone). Limit confusion and excuses from students if they miss an upload deadline.
The block displays both the server timezone and the student’s timezone (set in user settings). Note that assignment deadlines are correctly displayed for students as long as their timezone is set appropriately in their user settings (this would highlight an issue if the student is seeing the incorrect time listed next to their own name).
Download it here for Moodle 2.9: https://moodle.org/plugins/view/block_simple_clock