Significance of having goosebumps?
As a general rule, you might want to check wikipedia before posting here. On the other hand, I am glad you made me look the answer up.    

Goose-bumps warm you up a little. "During the formation of goose bumps, the body is warmed from the muscle tension in piloerection." 

There are other reasons, which do not directly serve humans, but may be a remnant from evolution. In animals with fur, the erected hair makes thicker insulation and further protection from cold. "Goose bumps can also be a response to anger or fear: the erect hairs make the animal appear larger, in order to intimidate enemies." 

More on wikipedia: http://en.wikipedia.org/wiki/Goose_bumps