A winter wonderland may be filled with frozen water, but it's liquid water that birds crave. By providing water in your backyard via a heated bird bath all winter long, you'll see a wide range of thirsty birds visiting the bar for a quick drink.
I love my heated bird bath - a very simple plastic basin with a concealed heating element (to prevent shorts and increase the lifespan of the heater) mounted in a plain metal frame. The house finches, lesser goldfinches, and American goldfinches all enjoy simple sips, but it is the house sparrows that truly enjoy the bath - in every way. More than once this winter I've spied my sparrows happily splishing and splashing, even on the chilliest of days. Many backyard birders worry that bathing birds might freeze in winter, but in fact they're quite well insulated and moderately wet feathers are not harmful on most days. The birds themselves don't tend to bathe in the most severe cold, and after a bath they often sunbathe or otherwise dry themselves off and warm up.
Even in winter, never forget to clean your bird baths and keep them freshly filled. This is especially important with heated baths, since a dry bath can cause the heating element to malfunction. I need to remember to refill mine more frequently, but whenever I see the birds balancing nearly headfirst for a quick sip, it's a great reminder!