Now's the time to think about saving seeds for next year if you haven't already. With the economy the way it is and other things so uncertain, you may be very glad you have your own seed next year.
Of course, if you've planted seed that's been genetically modified, your plants won't produce viable seed and IF you should get a seed or two that will grow, you're doing something illegal by saving it. (Thanks, Monsanto)
If you planted hybrids, the seed may not produce true to type. That's a way of saying that if you plant saved seed from a hybrid tomato that was large and juicy, you may get a small, dry tomato from it.
Heirloom, organic seeds will grow true to their type. If you have big juicy tomatoes this year and you save seed, you'll have big juicy tomatoes from it next year. (Which is not to say that the weather doesn't have anything to do with it!)
So save seeds. From lettuce, from radishes, from squash and melons and corn and peppers and yes, tomatoes. Be sure to let fleshy produce get ripe before saving the seed. Much of what we eat is "green," in that it isn't ripe when we eat it. Sweet corn, squash and peppers, etc., need to mature to a stage that seems inedible to us. Corn needs to be dry and hard, squash will become hard shelled and maybe gnarled or warty, peppers will change color and become dry and wither and so on.
When you have saved your seed, store it carefully in a dry, cool place. Next year, bypass the seed racks and catalogs and delight yourself in planting your own saved seed.