Keep in mind that tomatoes harvested after the vines die are less acidic so care must be taken when canning the ripe fruit. For more information on canning safety consult the USDA Guide to Home Canning.
Harvest green tomatoes at the first frost when you know the plants will die and the fruit will no longer be able to vine-ripen. Sort the tomatoes by maturity (pink, white to very light green, and darker green) and then layer in a box or tray with newspaper and story in a cool, dark place. Light green tomatoes will ripen in about 2 weeks, and darker green tomatoes will ripen in 3 or 4 weeks.
As the tomatoes ripen, they produce ethylene gas which stimulates ripening in other fruit. This is why bananas stored with apples will ripen more quickly. Here is a bulletin with more detailed instructions for ripening green tomatoes.
Green Tomato Recipes
Get creative! There are many uses for green tomatoes, including picles, chutneys, pies, salads, and salsas. Here are few to get you started:
Pickled Sweet Green Tomatoes
Spiced Green Tomatoes
Green Tomato Pie
Fried Green Tomatoes
And some very creative recipes including salsa, pasta sauce, and eggs benedict!