From my understanding feudalism was a largely agrarian-based economy, with most peasants living in small villages in the countryside working the land, and most of the nobility living in castles or manors.
If this is the case, who lived in the cities?
The Livery Companies of the City of London should give you a good idea of what kinds of activities city-dwellers were up to in Medieval times. The Livery Companies are 110 guilds and trade associations in London, the earliest dating back to 1327. In 1515, there were already 48 of them, and the trades they represented should give you a good idea of what types of people lived in London or any similar European city in the Middle Ages.
I would list them all here, but it's a long list. Know that London's City Aldermen ranked them by order of importance in 1515, with each subsequent Livery Company that formed being ranked thereafter chronologically. The original ranking was by economic/political influence on the city government, which should also give you some idea of what the economy was like in 1515.
If you're interested in an earlier time frame, here is a good rundown of the kinds of trades being performed in London between 800-1216.
A lot of the guilds are what you'd expect and in general terms, they aren't all that much different than today. The industries represented include the food industry, medical industry, garment industry, metalworking, shipping, transportation/horses, toolmaking/weapons manufacturing, construction/engineering, law/government, and entertainment.