Countries with no extradition treaty with the US:
Afghanistan, Algeria, Andorra, Angola, Armenia, Bahrain, Bangladesh, Bosnia and Herzegovina, Brunei, Burkina Faso, Burundi, Cambodia, Cameroon, Cape Verde, Central African Republic, Chad, China (People's Republic of China), Union of the Comoros, Congo, Democratic Republic of the, Cote d' Ivoire, Djibouti, Equatorial Guinea, Ethiopia, Gabon, Guinea, Guinea-Bissau, Indonesia, Jordan, Kuwait, Laos, Lebanon, Libya, Madagascar, Maldives, Mali, Marshall Islands, Mauritania, Micronesia, Moldova, Mongolia, Mozambique, Myanmar, Namibia, Nepal, Niger, Oman, Qatar, Russian Federation, Rwanda, São Tomé and Príncipe, Saudi Arabia, Senegal, Serbia and Montenegro, Somalia, Sudan, Syria, Togo, Tunisia, Uganda, Vanuatu, Vietnam, Western Samoa, Yemen, and Zimbabwe.
Countries with neither diplomatic relations or extradition treaties:
Bhutan, Iran, North Korea, and the Republic of China (Taiwan) (which the United States does not consider a country under the One-China Policy).
Source: http://en.wikipedia.org/wiki/Extradition_law_in_the_United_States