You could try covering them with plastic to help hold in heat. I kinda lean toward bringing them in the house though, since I'm pretty sure it freezes a lot where you are. The berries should overwinter fine on their own (mulch them good) but I can't see the tomato, peppers, or squash being happy in the cold.
And how do you still have plants? Mine have already given up the ghost and turned yellow and dead. I'm going to till the garden next weekend and plant a cover crop. I just started up the Aerogarden and planted a bunch of herbs, otherwise its whatever the farmer's market has available (and how often I succumb to supermarket stuff) from now till next May. *sigh*