Wife and I just got back yesterday from a long weekend trip to Hilton Head, and while there we did a day trip out to Daufuskie Island. Took the ferry out there (no road access), and rented a golf cart to cruise around in. It was pretty cool. The island is largely unmolested, and even the "developed" areas are pretty rustic. There's some old, historic buildings and things to see, rooted in Gullah history. It was a fun day.
If you're in the area and have a day to burn, I'd recommend it. Just go there with the proper expectations. It's not the Ritz Carlton. But it has wildlife, large areas of unspoiled nature, and nice views of the water. And the docking skills of the ferry captain were awesome!