Many processes in the body are effected and regulated by highly specialized protein molecules: These molecules certainly deserve the name "biochemical nanomachines". Recent progress in single-molecule experiments and corresponding simulations with supercomputers enable us to watch these "nanomachines" at work, revealing a host of astounding mechanisms. Examples are the fine-tuned movements of the binding pocket of a receptor protein locking into its ligand molecule and the forced unfolding of titin, which acts as a molecular shock absorber to protect muscle cells. At present, we are not capable of designing such high precision machines, but we are beginning to understand their working principles and to simulate and predict their function.