The Pong clock
The Pong Clock is an art project and a clock-- it's a physical installation of Pong that shows the time:
Every minute the right side wins; every hour the left side wins. Here's a GIF movie that demonstrates the effect.
This isn't just a concept-- according to
the website, sales start in January 2006, though I expect this is one of those custom "if you have to ask how much it costs you can't afford it" items.
For the more frugal art / old game / clock enthusiasts among us, there is a screensaver available on the website. You can't direct link to anything in the site, so to get there, click Portfolio, Browse, Miscellaneous, Pong clock. The screensaver link is under the picture.