Probably one of the geekiest, most useless pieces of technology I’ve ever had the pleasure of stumbling across online is the Dynaflex Powerball Gyroscope. Thinkgeek says:

In addition to being a fun and intriguing gadget, the Powerball also is a great way to directly experience the Gyroscopic Effect (you know - angular momentum, linear momentum, centripetal force, precession and all those neat physics properties). It’s a compact little display of Newtonian physics at it’s best.

The Powerball Gyroscope has these features:

* Perfectly balanced and capable of rotations up to an incredible 15,000 rpm
* Built-in blue LED light - glows brighter as gyro rotates faster
* A fun and practical demonstration of physics properties (centripetal force, etc.)
* High-quality materials and construction
* Great strengthening tool
* Can provide gentle rehab for carpal tunnel, RSI, arthritis, tendonitis
* Unique digital counter that displays rpm and/or highest speed
* Does not require batteries

Ok, so it spins really fast. But it looks cool.