One (completely personal) warning for black tomatoes, do NOT go for Purple Calabash. It tastes NOTHING like any other black tomato and the color takes some getting used to (unlike the normal dusky rose or dark pink with a green wash, PC is sort of bruise shade). And I REALLY don't like the tomato (I've heard people say it tastes like it's be marinated in red wine, or like Marsala sauce. To me it just tastes spoiled) PC is a rather odd tomato in many respects anyway (it's the only one I can differentiate from others from the SEEDS alone)
Speaking of blacks, Nagaraclang can be interesting, if you can find it (I got mine from someone on ebay who I don't think is there anymore) Supposedly it's the ideal tomato for you if you live somewhere where it's always rainy since the flowers shed water (I always joked I should plant it next to some Cheeseman's tomatoes (L. cheesemanii) which are supposed to be ultra drought tolerant on the grounds that t least ONE of them should produce something!)