Put your toms in a drawer along with an over ripe banana and they will turn red or put a yellow banana in and it will take a bit longer. They ripen due to the gas given off by bananass and the bananas ripen from the gas given off from the toms .
Please be warned - this really only works if you have a drawer!
Or else - somebody hasn't told my tomatoes that this is supposed to work... I've been trying it for years (no, not with the same tomatoes over several years!
), and since I don't have a drawer, I put them into a closed polythene bag. Either this doesn't work, or I'm just too impatient...
Actually, I also read some years ago that just the banana skins have the same effect. (I think I read that in Russia they do this, because otherwise they'll never get their tomatoes ripe in some areas...) Which is why my tomato plants are always "decorated" with banana skins that are rapidly turning black!