Sugru - derived from the Irish language "sugradh" for "play" is a multi purpose non-slumping version of Silicone that resembles modeling clay or Plasticene.
Sugru was developed by Irish sculptor Jane Ni Dhulchaointig resulting from her need to hack stuff to make them function better. Sugru can be modeled just like clay, applied to the surface, shaped and then left to cure for 24 hours. On curing it forms a permanent bond with the host material and is waterproof, dishwater proof and flexible and can handle a temperature range from -60 to +180 degrees Celcius.
I can already think of a few places where I could use this product.
Here's Jane describing Sugru.