I picked up a fun little toy this week, the SparkFun AVR Oscilloscope Clock. It displays an analog clock on an oscilloscope in X-Y mode. Here's an image of it driving my BK Precision oscilloscope:
It comes as a small pre-assembled board that just needs power and a connection to your 'scope.
It has a ton of different display options which can be controlled from small push buttons.
It packs a lot of features including optional connection to a GPS for time synchronization, control from a USB or serial port, and you can modify and reprogram it's firmware.
Here it is operating with my Heathkit IO-4205
An earlier version was sold as a kit, but unfortunately the latest design is only offered as an assembled product, due to the heavy use of surface mount components.
It can be a fun way to show off a spare oscilloscope you have lying around. It can even be useful as a piece of test equipment: it has a mode where it can act as a function generator and another where it can
operate as a serial port terminal.