VooDoo dolls are probably the most recognized symbol of the VooDoo religion. Interestingly enough, the dolls were not part of the original religion, either in Africa or Haiti. The earliest recorded serious use of the dolls, among voodoo worshippers, was in the New Orleans area in the early 1900's. As a matter of fact, most dolls that are available for sale are called "New Orleans VooDoo dolls"

VooDoo dolls are used as a focusing tool or an effigy for some VooDoo practitioners. They can be made from most any material, but are generally manufactured from local materials, such as clay and sticks and moss. The purpose that the doll is to be used for always affects the appearance of the doll. For example, a doll that is to be used in a fertility rite will have exaggerated female features. A doll that is to be used to hex or cause injury to a specific person will be made to look like that person and will ideally contain the hair or a personal item belonging to the target.

One well-known practice with VooDoo dolls is the sticking of pins into the doll. Dolls can be used to either attract things or to repel things. If the user wants to attract something to the target of the doll (can also be themselves) they stick a white pin into the part of the doll that best represents the desire. For example, if Love is the desired result of the doll, the practitioner would stick a white pin into the dolls heart. If pain or injury was the purpose, the pin would be stuck into the area the user wanted to hurt. Colored pins are used to deflect or remove things from the target. Pain, diseases, curses or bad luck are some of the major symptoms that VooDoo dolls are used to remove from people. The doll is then "cursed" and must be disposed of correctly before the removal is complete. The proper disposal of a cursed doll is as follows: "On a Saturday, place the doll (or object) in a clean white cloth, dig a hole in the earth, far away from your home (on Hallowed ground if possible), place the cloth wrapped dolls in the hole and burn them. Then, cover the ashes which remain with Holy Water or May Water and cover the hole over with the dirt. The earth will recycle that negative energy very quickly and turn it into positively and Blessings. When you return home afterwards, bathe very well, adding some Holy Water or May Water to your bath.

http://www.vudutuu.com/vuduhistory.html
http://www.witches.net/voodoodolls.htm
http://www.folkart.com/voodooshop/faq-dolls.htm#q1