Daggerfall players may remember that from time to time, cities would celebrate holidays and so on. The player would be notified of this when entering the city/village, and there were some small benefits involved - discounts on temple blessings, for instance. But the main point was that it created an illusion that the local populace lead lives of their own. Which, of course, was all the more believeable since even the smaller cillages in TES II had rather large populations by TES V standards.
I'm thinking that something along these lines should work very well in Skyrim, although on a different scale. Let's say that every village has a market day once a week. On this day, farmers, mill workers, shepherds, hunters, miners etc will travel to the village centre. During the day, they will sell their own wares and buy wares from others. Come nightfall, they may choose to spend some septims at the local tavern, depending on their economy/mood/how long they have to travel.
For the player, this would mean that once every week, the town will be a much more buzzing place than usual. The roads leading in will be full of farmers, shepherds, millers, and other workers bringing their wares in by cartloads, or carrying it on their backs. The town itself will also be much more crowded, with many of the NPC you would otherwise meet only in the wild now in the town itself - that means streets packed with people, even in smaller villages. Not only that, there will also be more stalls, where good deals can be made. And I'm imagining quite a few brawls between different NPCs in the local taverns at nighttime.
Now, I'm mainly thinking of immersion here - just something to keep the town from being the same every time you enter, and to enhance the illusion that the NPCs of Tamriel lead lives independently of what the PC does. But it might serve to add some standard radiant quests as well - some of the people coming to the town may need escorts, the local guard may need strengthening of their patrols to guard against increased bandit activity at this time of week. Not to mention - market day will be the day to find items that can be bought. Sure, the shops will be open the rest of the week. But during market day, there are plenty more vendors available, so a much bigger amount of ingredients, ore, ingots, and so on will be available for purchase. And it means a chance to meet NPCs you would normally only meet way out in the wilderness.
In the same manner, other events may also be added. Some days may be holidays, which would mean a quiter town than usual - and so on. Admittedly, nothing like market days existed in TES II - but the idea of "seasonal" events did, and I'd like to see such events in the newer TES-games as well.