The work-force was positively impacted. Because there were few to survive the plague, there was a much smaller amount of people to work. So, the people able to work were paid at a much higher rate.
Cities
Cities declined greatly as a result of the plague. When the number of people began to decrease, the cities simply fell apart. There were then few to fill job positions and run the government.
Catholic Church
Catholic Churches began to thrive during this time. Once people were infected with the virus, they turned to the church to save them. It is believed that they were even the number one influence in all of Europe. However, when the catholic church split off into other religions in the 1500s, their power slightly declined.
Population
Obviously, a plague will greatly impact a population and usually in a negative way. As more and more people get infected, deaths occur. A popular theory for this period in time is that an entire generation of people were basically wiped out due to this plague.