Most year-end charitable givers can't hold a candle to the generosity of the Bill and Melinda Gates Foundation. The charitable foundation headed by Gates' father has made a $100 million challenge grant to the Rotary Foundation's campaign to help end polio in the world.

Those too young to remember the scourge of polio may have trouble comprehending the scope of the disease. Before Rotary Internation's eradication effort began in 1988, about 1,000 children a day were paralyzed by the disease.

Today, according to Rotary president Wilfrid Wilkinson, there are only four countries -- Afghanistan, India, Nigeria and Pakistan -- that are still polio-endemic. Instead of 1,000 cases a day, the disease now strikes about 1,000 a year.

The foundation has raised about $600 million to support polio eradication efforts in 122 countries. The effort is at a critical juncture. Mass immunization efforts through the World Health Organization and UNICEF will continue.