Boffins at Bristol University in the UK have come up with a special skin for spaceships that can heal itself if it gets torn, in a similar way to how human skin works. I cam across the following explanation in the New scientist:
The researchers came up with a similar idea for protecting spacecraft. They fabricated a composite laminate material containing hundreds of hollow glass filaments 60 microns (thousandths of a millimetre) wide, each with an inner chamber of 30 microns in diameter. Half of the filaments are filled with an epoxy polymer or resin and the other half filled with a chemical agent that reacts with the polymer to form a very strong and hard substance.
The glass filaments are designed to crack easily when the overall composite material is damaged, which causes both chemicals to leak out and rapidly plug the resulting crack or hole. “We’ve demonstrated we can restore strength by doing this,” Bond says, “and that it can stand the space environment.”
It seems a pretty cool idea to me, until somebody invents a proper force field self repairing battle cruisers may be the answer :).