Binary Bash Clock. Relies on bc.

binaryClock.sh

#!/bin/bash
# Binary Bash Clock
# Spike Snell - 2012
while true;
 do
 clear
  hour=$(date +%H)
  minute=$(date +%M)
  second=$(date +%S)
  hour_binary=$(echo "ibase=10;obase=2;$hour" | bc)
  minute_binary=$(echo "ibase=10;obase=2;$minute" | bc)
  second_binary=$(echo "ibase=10;obase=2;$second" | bc)
  printf "%06d\n" "$hour_binary"
  printf "%06d\n" "$minute_binary"
  printf "%06d" "$second_binary"
 sleep 1
done