Appearance always comes last in my assessment of a food's worthiness, but in this case, the astonishingly deep red color of a 'black' tomato is also a plus. It's true that we eat with our eyes as well as our mouths. Still, that deep color, which sometimes can look brownish with occasional streaks of green, has kept this tomato from commercial production. (More conventional farmers feel its odd appearance will keep it from selling well in the supermarkets.) Whatever. I can't remember the last time I bought a tomato in a supermarket anyway!
Most black tomatoes originated from the Crimean peninsula in the Ukraine where hot summers encourage the development of sugars and darker, mahogany-hued pigments. Also delicious is the Black Cherry (exactly as it sounds, a deep ruby-fleshed cherry tomato) and Cherokee Purple. Here's an excellent listing of varieties of black tomatoes (with pictures!) from the wonderful people at Heirloom Tomato Plants.
(Image: Dana Velden)