I was surprised when I could not find any persistence of vision projects on the web using a basic stamp.
Initially I used a piezo speaker to beep each time the pov pattern was complete. This allows you to synchronize your waving motion with the message display. The final pov implementation uses a Memsic accelerometer to figure out when to reverse flash order.
Step 1: Build the Circuit
I used the integrated bar LED DIP, but a row of single LEDs should work just fine.
Step 2: Code the BS2
Edit pov.bs2 with your pattern and upload to the basic stamp. The code should not be difficult to figure out. The piezo version is still supported: set USE_MEMSIC to 0. The light pattern can be found in the DATA directive near the bottom of the file.