Freezing tomatoes is a great way to save for winter, and a great thing to do when you seem to have way too many. Tomatoes may be frozen whole, sliced, chopped, or puréed. Tomatoes should be seasoned after freezing (just before serving), not before.
Select firm, ripe tomatoes. Sort them, discarding any that are spoiled. Wash them, and cut away any damaged parts. Dry them by blotting with a paper towel or leave them to dry in a well circulated area. Put them in a ziplock bag, and place in the freezer. You might prefer to freeze them on a cookie sheet before putting them in the bag, it will help take them out one-by-one later.
Frozen tomatoes are best used in cooked foods such as soups, sauces and stews because they become mushy when they're thawed. Skins are easily removed after freezing by running them under warm water.
It is generally recommended frozen vegetables be eaten within about 8 months for best quality.