The U.S. Department of State provides basic information to U.S. citizens about travel to Cameroon. Complete information regarding this travel to Cameroon can be found at:
http://travel.state.gov/travel/cis_pa_tw/cis/cis_1081.html#country

Individuals wishing to obtain visas for entry into Cameroon should contact the Consular Section of the Embassy of Cameroon. 

Embassy of the Republic of Cameroon
1700 Wisconsin Ave. N.W.
Washington, DC 20007
Phone: (202) 265-8790
Fax:     (202) 387-3826
Email: mail@cameroonembassyusa.org
Website: http://www.ambacam-usa.org/

The Trade Information Center of the International Trade Administration maintains information on conducting business in Cameroon.  This information can be found at:
http://export.gov/cameroon/

Please direct inquiries regarding contacting Cameroonian officials to the Embassy of the Republic of Cameroon.  Their contact information is:

Embassy of the Republic of Cameroon
1700 Wisconsin Ave. N.W.
Washington, DC 20007
Phone: (202) 265-8790
Fax:     (202) 387-3826
Email: mail@cameroonembassyusa.org
Website: http://www.ambacam-usa.org/ 

You may also want to contact the US Embassy in Yaounde, Cameroon at the following address:

The United States Embassy in Cameroon
Avenue Rosa Parks
P.O. Box 817
Yaounde
Cameroon
Phone: (237) 2220-1500
Fax: (237) 2220-1500x4531