Whether you're biking or driving, everyone has to share the road, ideally in a safe way so no one gets hurt. These DIY signal gloves aren't the prettiest around, but a little reflective tape on a pair of warm gloves will make sure any car on the road sees your hand signals and knows when you need to change lanes or turn well ahead of time.
Instructables user harmless_matt used a pair of mittens that have flip-up fingers so he could wear the gloves fingerless when he wasn't biking, and then bring down the signals for use when he was moving around down. Just extend your hand out so the reflective arrow catches the lights of the car (or is just in view of the drive) to indicate which direction you need to go. The reflective tape makes sure your signal is seen, and the arrow makes sure it's understood.
Granted, simple arrows aren't the same as internationally recognised hand signals, but arrows are probably less prone to misunderstanding. We've covered an automatic option before that requires some work, but this method will get you fixed up and out the door in moments. More importantly, they help keep everyone -- drivers and bikers -- safe on the roads.
Signal Gloves [Instructables]