Here's an interesting project I found on Indiegogo's site: a bicycle helmet which collects heart rate data. The helmet can feed the data to a smartphone using Bluetooth. As the helmet also has an accelerometer, the project owners are looking into the possibility of crash detection. Since bikes or helmets don't have airbags, I am not so sure what good a crash detection feature would do, but perhaps at some points sports clothing will get more protective.
In some ways this could be considered a solution looking for a problem to solve which already has a solution: Bluetooth-enabled heart-rate monitors already exist, and so do helmets. I suppose it could be argued that this saves the user a bit of hassle. But the point here is that sensors such as heart-rate monitors are being "sewn" into other wearable devices.
This on-going collection of vital data has great potential. Let's get it on.