Not much is known of the life of St. Nicholas. He is said to have been generous to children and to the poor. St. Nicholas is the patron saint of children. Here is a link to a list of Saints.
St. Nicholas is said to have been born into a prosperous home. His parents died when he was a young man and he was left an inheritance. Nicholas used this inheritance to help a poor man support three daughters who otherwise would have been sold into prostitution to support the family home.
It was this gift giving that is the connection between the St. Nicholas of old and the Santa of the modern day. In the spirit of the gifts for the three children, people in Germany, Switzerland and the Netherlands began to give each other gifts at Christmas. Santa Claus is, after a few mutations, St. Nicholas.
Here is a link to the website of Adbusters. Adbusters suggests you should buy as little as you get away with at Christmas and offers often insightful critiques of consumer culture.
It is said Nicholas brought back to life two or three boys who had been cut-up and tossed in a brine-tub by an innkeeper. The innkeeper was going to sell the boys as pickled pork. It is not known how Nicholas performed this feat.