Your average motorist is more used to sharing the road with other vehicles than cyclists. So instead of just relying on your arms to safely signal an upcoming turn, consider these $42 turn signal gloves which let both cyclists and motorists alike know where you're headed.
Usable with an included set of bike gloves or your own pair once they've been enhanced with a bit of velcro, the LEDs are triggered via a thumb-accessible button and can be used to signal a turn, or continuously flash for enhanced nighttime visibility. On a fresh set of batteries they'll flash for 120 hours straight, so you can safely get to and from work for days on end, or manually flash an SOS distress if you find yourself lost after a ride in the woods.
[Doppelganger via Damn Geeky]