Less than two months after Bill and Melinda Gates, with their friend Warren Buffet, challenged the wealthiest people in the US to give away the bulk of their money to charity, the billionaires are starting to roll in.

Paul Allen, co-founder of Microsoft and Forbes’ 37th-richest man in the world, last week announced he plans to give away the bulk of his estimated $13.5bn fortune to charity after his death. This is on top of the $1bn he has given away over the last 20 years via his personal foundation.

His pledge is the first one to follow after the Gates’ and fellow multi-billionaire Buffett created The Giving Pledge, an initiative designed to encourage American billionaire families to pledge to give away “a majority” of their wealth to charity.

The Giving Pledge requires that the intended philanthropists make a public statement indicating their wish to give away their wealth. Pledgers will also attend an annual dinner to discuss their commitment.

Allen’s gift is one early fruit from the crusade the Gates’ appear to be waging to increase and improve philanthropy. Earlier this month the Bill and Melinda Gates Foundation made a $3.7m donation to the Rockerfeller Philanthropy Advisers to establish a programme which aims to improve donor education.

The philanthropy advisers will create a series of at least two dozen documents advising donors of all levels on how to make the most effective use of their giving, all of which will be available for free on the Rockerfeller website.

While the Giving Pledge is initially focused on the US, the Rockefeller philanthropy programme is targeting Europe and Asia, both initiatives may well end up having a more global scope.