Do you have a picture to post? There are several reasons that a tomato leaf might curl. Malnutrition, pests, and virus are possibilities.
The solution depends on the cause.
I am 90% done with tomatoes this year. I have a few stragglers still producing but the plants are 6’ to 8’ tall and have stopped setting.
I planted early and harvested 124 lbs from 80 sq ft, 1.5 lbs per sq ft of garden. Made lots of spaghetti sauce and new friends, as well..
Cherokee Purple and Sunny Boy were best producers and best tasters as well...
I used blackstrap molasses and epsom salt this year along with compost tea. I also used only rainwater...did not see a single hornworm this year. Along with providing nutrition and building the soil, blackstrap is supposed to inhibit pests, even ants...
There is good info on molasses here:
http://www.ehow.com/info_7976252_organic-fertilizer-molasses.html