Telling you what time it is seems like a trivial task for any modern browser, however many leave the job to your operating system.
However, if you have hidden your clocks and need a way to tell what time it is from Firefox, Statusbar Date is the perfect add-on for the job.

Since I eliminated my wall calendar this year and started using Google Calendar to write down all my important dates, I have been catching myself from time to time looking up at the blank spot where the wall calendar used to be. While browsing through extensions I think I may have found one to help me get my date fix. the Date Picker/Calendar extension gives you a little date and time notification the bottom of the Firefox [...]