A french team of scientists has created elastic rubber that heals when cut :
(in english)
http://news.bbc.co.uk/2/hi/science/nature/7254939.stm
(in french)
http://www.lemonde.fr/sciences-et-en...?xtor=RSS-3208
Even though it's not done with nanomachines, we are moving in the realm of sci-fi on this one !
The amount of possible applications is pretty impressive.