The department of human resources in your state (or what ever Social Services goes by where you are) is a good place to start if you are having a problem. They even have emergency help for that once in a blue moon kind of thing. Be careful though because many states have a "life time limit" now, so if there is another way...
The phone book should have food bank listings though honestly around the holidays they are a bit hard to get help from them after a certain date. Also they tend to run a bit low in the summer when people forget that people get hungry. (So in July, if you have something to spare it's a great time to donate to your local food bank.)
If you or your child has a disability get to Social Security as soon as you can because even though it takes a minute to get approved, they take it all the way back to when you filed.
There are programs to help you get re-trained if you've lost your job. I need to look into the how and where of them so I'll get back to you on that.
Faith based groups often have programs or can tell you where there is help. Churches are great and there are even pagan centered programs here in the greater Detroit area. I'll post that at a later date also.
If you know there is a lay off coming try to set aside and buy ahead. I know when you are living pay check to paycheck that's hard but it's worth it when you are trying to pay those bills on a 40-60% of your pay. Green beans on sale? Buy an extra can for the Lay Off shelf. We wouldn't have made it through July without plotting ahead and the help of a good friend or two.
Your child's school is likely to have a few resources too, so check with them. It's better if you go to the social worker or a trusted teacher if you can.
There is programs to help with the heating and electric bills. The company them selves may have a program in place. There may be a state program.
Check into things BEFORE the crap hits the fan if you can. If you know that lay off is coming see if there is a program with the utility company that allows you to make a budget style payment. That way you are ahead of the game.
Sometimes there is no warning (like my hubby's recent 3 month sick leave) so it helps to keep a bit extra in the pantry. It's like not letting your gas tank get empty. Try to keep a little extra in the cabinet just in case. The kind of food that costs little but can go far... like rice, is a great extra food.