One day I was playing around with a compass and a magnet noticing how much fun it was to manipulate the compass rose as I moved the magnet around. I'm of the mindset that when it comes to fun, more is usually better, so I rounded up 500 compasses and some rare earth magnets and decided to turn what started as just a little silly but entertaining play time into an actual piece of furniture.
The compasses are inlaid into a custom table top underneath a piece of glass. The coasters were made to match - they also provide an inconspicuous home for the powerful rare earth magnets that affect the compasses.
Now I always know which way is north, and exactly where my cup of coffee is...er, so long as it's always on my compass table.
**Note, the reliability of compasses in mass quantities and close proximity decreases somewhat since compasses themselves are magnets. It still works, and actually results in some pretty cool patterns, but if you're looking for the table to be 100% accurate, I'd recommend not designing a table that places them so closely together. I'm a big fan of the way the table came out, as it's a toy just as much as it about the science of magnetism.**