The Nixie ("Numerical Indicator eXperimental") vacuum tube was invented in 1952, and commonly used in equipment displays up until the early 70's. They have long been replaced, but I love these classic pieces of electronic history. Although originally never used for time telling, today a clock is a great way to admire their beauty.
Oscilloscope display tubes (CRT's) have been around for even longer, and can also make interesting objects for displaying the time.
The following clock kits I've built, all utilise a low voltage micro-controller driven design, and have support for DCF77 which can set the time automatically from the atomic time standard transmitter in Frankfurt, Germany.