Villages
Whether you enter with a one or many day trip, it is well-worth the journey. see the top of this article for a more detailed listing.
Kola Nuts
Buy them in a town such as bandiagara and give them to people such as the village chiefs or elders. while seemingly a minor detail, they are inherited from a very old tradition and are much appreciated. plus, they allow visitors to interact in more authentic manner with people than just handing out money.