I am sitting here reading a book by the fireplace and waiting until dinner is done cooking. But what would a serf do on this day, November 27th 1116? There is not much daylight to labor in with the sun rising around 7:45 and setting around 3:50.
Medieval peasants, of course, did not keep day planners, or in fact leave any direct verbal records of their lives. But through archaeological evidence and extrapolation of attitudes from contemporary and later sources, we can still get an idea of those long cold nights for the high medieval peasantry.
The most important adjustment was sleep schedule. Where we do have something resembling schedules in medieval Europe, they differ between summer and winter. The Rule of Benedict, which undergirded daily life in many monastic communities, affords monks and nuns an earlier bedtime in the winter. Regulations for grammar schools and universities in late medieval German cities set a much later starting time on winter mornings.
In the latter case explicitly, part of the shift was due to the cost of candles that boys would have to supply. Candles and oil lamps were less likely to have been a factor in peasant homes. Lighting by fireplace/firepit was far more common, and served the side benefit of warmth. So fuel for fires would still have been a factor. And out-of-control fires were a perennial fear--our word "curfew" comes from a French expression for cover fire, although these regulations postdate 1100 and are typically associated with towns and cities. So signs point, first of all, to more hours of sleep.
Second, the use of fires to light and heat the home during dark afternoon-evenings provides some clues as to what type of labor might have been acceptable. Yes, labor--medieval agricultural manuals (admittedly, not directed at peasants) and manuscript illuminations often involve the "farm year", associating a particular type of labor with each month. There was no time off on a medieval farm.
A fireplace fire was considered sufficient light for meditative reading by Agnes Blannbekin in 14th century Vienna and sufficient light for writing letters (although his ink tended to freeze in the inkwell) by Paul LeJeune in 17th century Quebec, so there. These are not the tasks of 12th century serfs, of course. The Liber ruralium commodorum from c. 1300, however, assigns a notable job to "January" in terms of farm labor: the gathering of clay to make pots. Basic pottery is exactly the kind of task that would lend itself to being done by firelight. Furthermore, although the evidence for this is urban and later, there may have been a particular need for clay pots in wintertime when fires burned longer and larger. In Italian city-states, when a fire broke out in a neighborhood, residents would fill clay pots from the closest well and throw them at the burning building. The clay would shatter and produce a shower of water--premodern water balloons!
Most medieval peasants also made and repaired most of their own clothes. If men and women were spending the short daylight hours gathering clay and taking care of the other winter chores--caring for livestock in particular--it seems probable that the dark hours could be used for less intricate repair work.
What you're probably here for are tales of raucous, steamy winter nights in the old peasant village. Fortunately, contemporary archaeological evidence and extrapolation from later practices can help us out. Medieval peasants certainly did not live in anything resembling a consumer culture, but even village excavations turn up an often-surprisingly rich material life. One of the most common "fun-time" finds are actually game pieces! Although playing cards would not have been around, dice games and token games (like checkers) were popular.
Medieval aristocrats enjoyed singing and storytelling as entertainment, and there is absolutely no reason not to assume peasants did not have fun with songs and stories on winter evenings as well.
So far I've talked about "what", but I haven't broached one of the most important questions: with whom? At least in the later Middle Ages, peasant households were frequently centered on the nuclear family. However, it's clear that medieval people at all levels of society enjoying paying their friends and family visits.
Company was good; alcohol was also good. Brewing was an at-home activitiy for most of the Middle Ages. Judith Bennett describes how most of the time, families would produce enough for just themselves, but could increase production to sell if they were short of money or goods. Although she's discussing a later time period, I draw attention to this because of an assertion she makes that is not entirely supported by other sources. Bennett argues that extra ale production in the late Middle Ages did not an "unofficial tavern" make. Medieval women (usually) would sell their extra ale, but on a takeout basis rather than for consumption on the premises. However, court records show that medieval women absolutely brewed and sold ale on a contingent basis that was consumed in their homes, often by their friends--and to sometimes riotous effect. There's a case from a 14th century tavern where a fight broke out when one couple decided to, er, heat things up--on top of the checkers board currently in use by two other people.
Over the course of the 12th century, winters would get just a little more comfortable for the English upper classes. A rapid increase in grain exports to Scandinavia resulted in the mass import of salted fish for consumption, whale oil for lamp fuel, and furs for winter clothing and blankets. It's unlikely that this trade would have had very much direct impact on the lives of the lowest peasants, with the possible exception of salted (preserved) fish for food. (That's usually described as the food of medieval winters, although I'm not sure to what extent that refers to towns versus rural villages). And it's clear from Anglo-Saxon sources that winter among the early medieval English elite was widely perceived as a tough, brutal time.
But at least there was sleep and alcohol.
Edit: You might also be interested in two related answers of mine from last winter: