LED wizard Moritz Waldemeyer has snapped some lights onto a bike that illuminates the spokes with a smiling face, the universal sign for happiness. Each wheel only uses one LED that's set to strobe, with a microchip built into each that'll tell the light how fast the wheel is spinning and when to flash the lights. How much mileage you get out of it really depends on how much you like to see others happy, as you typically won't be able to enjoy the Joyrider's lights yourself (unless you go head over the handlebars).
Then again, the Joyrider is really only going to light up the world effectively at night, so maybe that snarling guy with a broken bottle raised in the air will stop chasing you. Two Joyriders were shown off at the ICA 2008 Gala earlier this year, where they were sold for over $3,600.