I thought it would be great to capture the energy used from bicycling to power devices, etc. I know it is possible but is there a device out there now that works?
Yes. We used to buy these little generators that mounted to the front fork. It had a small wheel on it that could be put in contact with the side of the front wheel. This would cause that little wheel to spin and generated enough to run your lights and maybe a horn. Google around and I bet u can find something.