What about some pickled green tomatoes?
http://homesicktexan.blogspot.com/2010/10/pickled-green-tomatoes.html

Make a tomato tart! Throw in a little feta and olives for a bit of Greek flavor or some bleu cheese and a few herbs for more of a French feel!

Chow-chow is a great way to make use of green tomatoes and other end-of-the-garden odds & ends. Here's a good recipe from this site:

http://www.food52.com/recipes/424_spicy_green_tomato_chow_chow

You can also substitute green tomatoes for cucumbers in just about any pickle recipe; I prefer them to cukes in bread & butter pickles.

Or slice them thinly and use them as you would zucchini in gratins. I made a gratin with green tomato and caramelized onion topped with breadcrumbs and parmesan that was quite tasty. You'd probably want something with a sweet or creamy note to offset the tartness of the tomatoes.

Thanks for the replies! They are still too green for any chance of them ever ripening, so we'll need to do something with them sooner than later. Chutney sounds interesting, as well as the frying...would still love to hear more ideas!

What a treat . . green fried tomatoes. Try them for Thanksgiving.

My friend Anita recently posted a great sounding recipe for a green tomato chutney: http://marriedwithdinner.com/2010/11/19/green_tomato_apple_chutney/

I would put them in a cool, dark, dry place, like a pantry or closet. They will continue to rippen, but slower. If you want to use some, take them out a day or two before and put in a window sill to ripen faster.