Here's a trick - when my tomato plants have a lot of fruit, I take a couple, squish 'em and "plant" them, putting about 1/2" of soil above them. This grows another plant, which can be transplanted when it's big enough, and the fruits are even sweeter. I learned this from my dad.
(My favorite plant grows tiny toms, about 1-1/2" around, and honestly, since last June, it has not stopped producing, and it's sweetness is that of a plum. I have never seen anything like it. The worst part is that I don't know the name of the variety!)