It's been a good few weeks for the Giving Pledge, the campaign started by Warren Buffett and Melinda and Bill Gates to encourage the very wealthy to pledge half or more of their fortunes to charity. Even Facebook founder Mark Zuckerberg signed up, vowing to donate at least half of his estimated $7 billion net worth going forward. By joining the pledge, many of these generous souls are simply doing what they've always done: investing in undervalued assets.

With a net worth that Forbes estimated at $1.2 billion, Joe Mansueto, CEO of Morningstar (Nasdaq: MORN), and his wife Rika also recently took the pledge. As Mansueto explained: "I think I knew for a long time that I wanted to give the bulk of what I earned away. The only thing I had to think through a little bit was, I know my situation now, but how could my situation change 20 years from now or 30 years from now?"

Buffett himself (and many others) have pondered a similar question, wondering whether it's better to give money away to today's many pressing needs, or to wait and give away more later, after they've accumulated more wealth. Either approach has its upside.

It's exciting to think of what all this money can do. Pledger Jon Huntsman and his wife Karen, wealthy via Huntsman (NYSE: HUN), are devoting most of their assets toward fighting cancer. Jeff Skoll, the first full-time employee at eBay (Nasdaq: EBAY), is investing in social entrepreneurs and making films to promote social ideas.

Undervalued assets
Carl Icahn, best known as an activist investor and thorn in the side of companies such as Genzyme (Nasdaq: GENZ) and Motorola (NYSE: MOT), is another pledge-signer, with a fortune estimated around $11 billion. The same boardroom warrior who pushed Genzyme to add certain board members and successfully urged Motorola to split itself up apparently has a softer side. About joining the Pledge, Icahn said: "Those who have benefited the most from our economic system have a responsibility to give back to society in a meaningful way. ... America's children, especially those from underprivileged backgrounds, are in a sense undervalued assets."

Fellow pledger Bernie Marcus, who made his estimated $1.5 billion with Home Depot (NYSE: HD), is also concerned about children, supporting the Georgia Aquarium and the Marcus Autism Center among other projects. "To make quarterly profits is one thing," Marcus has said, "but changing just one life is so much better."

Why leave all the charitable giving to America's wealthiest people? When Oracle (Nasdaq: ORCL) CEO Larry Ellison, reportedly worth close to $27 billion, joined the pledge, he explained that he long ago put the bulk of his assets into a trust, with the intention of giving at least 95% of it away. Ellison added: "Warren Buffett personally asked me to write this letter because he said I would be 'setting an example' and 'influencing others' to give. I hope he's right."

You may not be able to pledge 50% of your fortune, but you can still heed Buffett's call, even with a donation of just $50 or less.

In the spirit of Carl Icahn's vision of schools full of undervalued assets, consider joining our Foolanthropy campaign to benefit Thurgood Marshall Academy, an amazing school in an impoverished corner of our nation's capital. The Motley Fool has been helping the school for several years now, and we encourage you to consider chip in a little support. Even posting comments on our discussion boards and articles will generate money for the Academy.

Whatever you do with any of your dollars is an investment. Why not invest in a brighter future for hard-working students -- and possibly the world at large?

Longtime Fool contributor Selena Maranjian owns shares of Genzyme, Home Depot, and eBay. Home Depot is a Motley Fool Inside Value recommendation. eBay and Morningstar are Motley Fool Stock Advisor choices. Motley Fool Options has recommended a bull call spread position on eBay. The Fool owns shares of Morningstar and Oracle. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our investing newsletter services free for 30 days. The Motley Fool is Fools writing for Fools.