The Crusades had numerous consequences and effects. Three were particularly important. First, the city-states of northern Italy, especially Venice, Genoa, and Pisa, grew rich transporting goods and crusaders back and forth between Europe and the Middle East. As the transporters, the merchants, and the bankers of crusading expeditions, it was northern Italians that derived the greatest financial benefit from the invasions. The Crusades provided so much capital that the northern Italian cities evolved to become the banking center of Europe and the site of the Renaissance starting in the fifteenth century.
Second, the ideology surrounding the Crusades was to inspire European explorers and conquerors for centuries. The most obvious instance of this phenomenon was the Reconquest of Spain, which was explicitly seen through the lens of the crusading ideology at the time. In turn, the Reconquest was completed in 1492, precisely the same year that Christopher Columbus arrived in the Americas. With the subsequent invasions of South and Central America by the Spanish, the crusading spirit, of spreading Catholicism and seizing territory at the point of a sword, lived on.
Third, there was a new concern with a particularly intolerant form of religious purity among many Christian Europeans during and after the Crusades. One effect of this new focus was numerous outbreaks of anti-Semitic violence in Europe; many crusaders attacked Jewish communities in Europe while the crusaders were on their way to the Holy Land, and anti-Jewish laws were enacted by many kings and lords inspired by the fervent, intolerant new brand of Christian identity arising from the Crusades. Thus, going forward, European Christianity itself became harsher, more intolerant, and more warlike because of the Crusades.