Charleston [1] is rich in African American history, and a couple of operators specializing in this area are worth mentioning:
Al Miller’s Sites & Insights Tours (843/762-0051, www.sitesandinsightstours.com [2], $13–18) has several packages, including a Black History and Porgy & Bess Tour as well as a good combo city and island tour, all departing from the Visitors Center.
Alphonso Brown’s Gullah Tours (843/763-7551, www.gullahtours.com [3]), featuring stories told in the Gullah dialect, all leave from Gallery Chuma at 43 John St. near the Visitors Center Monday–Friday at 11 a.m. and 1 p.m. and Saturday at 11 a.m., 1 p.m., and 3 p.m.
Links:
[1] http://www.moon.com/destinations/charleston-savannah/charleston
[2] http://www.sitesandinsightstours.com
[3] http://www.gullahtours.com