Nick Sayer created this simple desk clock that gets time from GPS:
GPS is best known as a ubiquitous, accurate positioning system (obvious from the name), but the way it actually works requires distributing hyper-accurate time information. This makes it possible (and, actually, pretty easy) to make a clock that you never have to set as long as it gets good GPS reception.
Yes, this is way overkill… but GPS is getting so cheap that you might as well.
The source code is available on GitHub:
Nick has hacked together a tenth digit for the clock:
Here is a video of the GPS clock in slow motion: