While there is great variety among the eggplants in the species S. melongene, some of the more unusual eggplants are in the tomato fruited species, S. integrifolium. These are red and orange fruited plants often grown in Asia and Africa. One gaining popularity in America is listed as 'Turkish Eggplant' or 'Turkish Italian Eggplant'. The flesh is softer than S. melongene, more like a tomato, and the fruits only grow to about 2" in diameter. I've often seen them described as being somewhat bitter, but my local Extension agent strongly disagrees and is going to prove their sweetness to me this summer. I'm looking forward to it.
The National Gardening Bureau (NGB) has designated 2008 the Year of the Eggplant. You can visit the NGB at www.ngb.org.