We recently saw the Turn Signal Jacket. Good stuff, but not great if you live in a hot climate. The alternative? The Bicycle Direction and Brake Lamp with 8-tune Horn. Looks like it attaches with ease and available here for a measly $15. Course, to use the turn signal you have to hit a ‘far from integrated button’ partially defeating the safety it hopefully achieves. The brake light can be hooked up to the brakes, though.