The texts that Gullah people have preserved have been in languages spoken in Sierra Leone & surrounding areas.
Goodwine, a native Gullah speaker, is an advocate for the Gullah culture who spoke to the United Nations' 55th session. She created the Gullah/Geechee Sea Island Coalition to help inform people of the culture because of the "native islander displacement" in Hilton Head. She also helped create & sustain "the Gullah excursion," which is a festivel that celebrates Gullah culture.
The interesting part about Gullah is how it developed and became so isolated. Since the slave owners had lower resistances to diseases, they left the slaves alone during rainy seasons when the diseases were prevelant. The slaves were able to follow their own traditions & culture without very much interference.
This is a Gullah site which offers an overview, audio clips, teacher resources, & folk tales.

Gives a brief overview of the origin of Gullah and why the dialect is concentrated in Georgia & South Carolina.
An exhibit by the Children's Muesum of Houston, which features Gullah culture and language.
This site offers educational resources for Gullah: Lesson plans, field trips, resources, etc.