What were some of the long-term effects of the Columbian Exchange?

The Columbian Exchange describes a period of time during the Age of Exploration (1500-1700, approximately) where the Old World and New World exchanged plants, animals, and pathogens through intentional and unintentional contacts with each other.  Vegetables such as squash and tomatoes from the New World helped to feed the Old World, thus driving up birth rates and longevity rates for Europeans.  This in turn led to more colonization as Europe became more crowded.  Diseases such as smallpox and diphtheria wiped out up to ninety percent of native Americans, thus allowing Hernan Cortez's small band of Spanish conquistadors to wipe out the Aztec Empire.  Spanish horses acquired by the Plains Indians allowed these tribes to become excellent horsemen who could follow the buffalo throughout the grazing season.  In New England, pigs and cattle escaped their fences and rooted through native crops.  While these crops were not planted in rows in the typical English fashion of the time, the settlers thought that their livestock were only eating wild plants--this caused conflict with the natives who lived in the area.  Tobacco from the Americas would become an international sensation--John Rolfe's hybrid tobacco made of native American and Caribbean strain was both flavorful and prolific, thus allowing people in the Middle East and Asia to smoke and chew the stimulant.  The tobacco trade in turn made England rich thanks to shipping laws.  The need for laborers who would not succumb to malaria led to the importation of African slaves into the New World starting in 1619.  North America, especially the northeastern areas, had a shortage of earthworms--forests were often filled with dead leaves which easily caught fire when the native Americans needed to burn new areas for their fields.  Unwittingly, English settlers brought earthworms with them when they brought over plant material.  These worms reproduced rapidly and created humus from the leaves on the forest floor.  To this day, mankind is forever changed by the Columbian Exchange.