The answer is: The Carter Center
After losing the presidential election, former U.S. President Jimmy Carter founded The Carter Center. It is a non-profit, nongovernmental organization, established in 1982 in cooperation with the Emory University. Carter's wife Rosalynn was involved in this project too.
The Center is located in Copenhill, in Atlanta, Georgia, adjacent to the Jimmy Carter Library and Museum.
The Carter Center's goal is to advance human rights, alleviate human suffering and improving the quality of life for people in poor countries. Some of the Center's projects are: monitoring local elections, supporting local democratic institutions, mediating conflicts and helping the victims of human rights abuse.
In 2002, President Carter received the Nobel Piece Prize for his humanitarian work.