There are many different concepts to what the soul is and what it does to benefit the body. From what has already been posted its been established that the soul gives us a conscience. (Although that is up for debate). The fact of the matter is the soul can be defined in many ways and forms and is most likely interpreted based on a person's path or lifestyle.
For example, in Christianity the soul is based upon the teaching of both the Old Testament and New Testament. The majority of Christians understand the soul as a reality distinct from, yet integrally connected with, the body. Its characteristics are described in moral, spiritual, and philosophical terms. When people die their souls will be judged by God and determined to spend an eternity in heaven or in hell.
In Hinduism, this soul is defined as the individual Self. The term "soul" is misleading as it implies an object possessed, whereas Self signifies the subject which perceives all objects. This self is held to be distinct from the various mental faculties such as desires, thinking, understanding, reasoning and self-image (ego), all of which are considered to be part of(nature).
Some of the above facts have been researched and are direct quotes from online references.