Who/Why are Minutemen?

According to Chris Simcox, Minutemen are "Concerned Citizens Leading the effort to secure our borders." And he's exactly right. His statement is continued with this link. Why do we need minutemen? As per the explanation, a lack of border security has prompted the need for action to support Homeland Security.

Oh, and for those of you who want to donate...click the word "donate."

Remember, America is a nation of unity and not diversity.
Sincerely,
The Samaritan