Part of the reason we keep so many chickens (usually around twenty hens), as I wrote about back here, is that we get just enough eggs through winter to have one or two each a day. In spring we will get up to twenty eggs a day and in winter it will be two or three eggs (so we have to eat some bacon with breakfast!). You can use some tricks to encourage chickens to lay through winter, however we prefer to give the hens a break.
There are a few reasons for the decrease in egg production. For the most part it is triggered by the day length, apparently when day length is less than 14 hours egg production will decrease. See this article for more details. For this reason, lights in the hen house can be used to simulate longer days. We are near the equator, so our day length only varies from 10 and a bit hours at winter solstice to just under 14 hours at summer solstice (its a wonder our hens lay at all!), so we don't experience the complete lack of eggs that may occur with very short days further from the equator. Here's some more information from another blogger who uses lights.
We also try to keep young hens in our flock by hatching more chicks each year and culling older hens. We find that pullets who just started to lay in spring will lay better through the subsequent winter compared to older birds. Its a good idea to have a rotation plan before you get chickens.
In autumn chickens go through a moult where they lose all their feathers. They typically don't lay during this period as their body is regenerating and growing new feathers. Each individual chicken will moult at different times with different severity, so we usually get a few eggs during this time as each hen takes a break.
Its important to feed chickens plenty of high energy feed during the colder months, from when they are moulting until spring, as they will be using lots of energy to regrow feathers and to keep warm in the cooler months. If I was more organised I would make sure they had lots of meal worms.
If its not winter, and your hens are not laying, it could be due to a few other issues, see this post for more information.
Are you hens laying at the moment? Do you use any strategies to have eggs in winter?