Astronomy

If you somehow got rid of your rest mass to move at the speed of causality, two things would happen: first, you'd experience no time; second, you'd instantly crash into your destination and die in a rather energetic way. That's the neat thing about photons; from a photon's POV time and distance do not exist. A photon, from its POV, is emitted and absorbed at the same time in the same place.

Much more interesting is having rest mass and moving at a high fraction of c: http://gamelab.mit.edu/games/a-slower-speed-of-light/