I said I might have something for today, and I do - though it is small. In honor of the 4th of July, when world building how many of you take into consideration holidays and festivals? We may scoff at them now a days (yay day off, what do you mean it's not just national "sleep in until 10" day?) but the meaning, and relevance, behind festivals is much larger in older societies, and especially in feudal ones.
Festivals, and other celebrations, were a great time for peasants and workers because they got to take time off and just enjoy the sites and sounds of what was going on. Often there would be gatherings at specific locations and you'd get to see people you didn't often see. Religious ceremonies were common, and with those also came more political machinations. Weddings could happen, or were often announced.
The point is, they were things to really look forward to, and they also showed a lot by how a culture worked. How? Because festivals were often days when the rules were broken for many things - which just means that the rules left unbroken are even more important. They can also be used to show how one group feels/acts towards their peasants as opposed to the other. For example, in Legend of the Five Rings the Scorpion clan are not particularly good to their peasants. In fact, they can be very harsh and demanding. However, the Scorpion also have more festivals and holidays for their peasants as well. This, in turn, keeps the morale of the peasants up and keeps things working smoothly. The Unicorn clan on the other hand treat their peasants very well, but have significantly less holidays and festivals for time off.
So, how do the cultures in your game world handle this?