The clock in the mountain: 10 curious side projects of tech's rich and famous

In their spare time, and with copious amounts of cash, these tech giants indulge in obsessions from space travel to cheating death.

Dave Barry, Stephen King, and Amy Tan are among a slew of very successful authors who participate in a very different kind of side project: the Rock Bottom Remainders, a band that gives performances (like the one you can see here) to raise money for literacy causes. A lot of tech giants have their own side projects, some of them philanthropic -- but in keeping with their personality and resources, they tend to be a lot more grandiose and weird than this literary garage band.

This slideshow originally appeared on ITworld.com

Jeff Bezos: The Clock of the Long Now

Amazon founder Jeff Bezos has put his billions into some pretty quixotic ventures -- a secretive private rocket company, the Washington Post -- but for sheer scope and oddness, few side projects can rival the Clock of the Long Now. A project of the Long Now Foundation, to which Bezos has donated millions, the clock is being built deep inside a Texas mountain and is intended to function for 10,000 years, outlasting our current civilization and encouraging humans to think in the very long term. It's not entirely practical, but then, neither is owning a print newspaper in 2014.

Bill Gates speaks at a "Reinvent The Toilet" competition in 2012. REUTERS/Anthony Bolante

Bill Gates: Philanthropy

Over the past decade, Microsoft co-founder Bill Gates has been famous for using his foundation as an instrument for his vision of social change. He's spent billions on attempting to, among other things, fight AIDS and reinvent the toilet. His process has come under criticism, though, for offering high-tech solutions to low-tech problems, even though Gates himself would prioritize a malaria vaccine over worldwide Internet access.

Ellison at the Louis Vuitton Cup challenger series yacht race. REUTERS/Peter Andrews

Larry Ellison: Yachting

Oracle founder Larry Ellison is an avid yachter, at one point owning one of the largest yachts in the world. He's also been a fixture on the yacht-racing circuit, instrumental in helping the U.S. become an America's Cup power again after some years of foreign dominance. He also helped bring the race itself to the San Francisco Bay Area, which resulted in a less than enthusiastic reaction from the city. In a somewhat more quixotic quest, Ellison has also declared that "death makes me very angry" and has set up a foundation to defeat it.

Brin speaks with attendees following the Life Sciences Breakthrough Prize announcement. REUTERS/Robert Galbraith

Sergey Brin: Protecting and strengthening the body (of Sergey Brin)

Speaking of overcoming the limits of our mortal form, Google co-founder Sergey Brin has donated millions to Parkinson's disease research, not least because genetic testing reveals that he has, by his estimates, about a 50% chance of developing the disease at some point during his lifetime. His worries about the condition have also driven him into a number of exercise regimes designed to strengthen his body and improve his balance, including yoga, gymnastics, acrobatics, and platform diving.

Elon Musk: The Hyperloop

Elon Musk made his millions as one of the early employees at PayPal, but two of his side projects -- the private space company SpaceX and the electric car manufacturer Tesla -- have become successful businesses in their own right, so let's concentrate on a somewhat more harebrained scheme: the Hyperloop, a giant pneumatic tube that would send capsules and passengers rocketing from the San Francisco Bay Area to the Los Angeles Basin at 800 miles an hour. Intended to replace California's financially troubled high-speed rail initiative, the proposal was dismissed as a flight of fancy by transportation advocates -- but then, radical ideas always meet resistance, don't they?

Peter Thiel: Seasteading

Another PayPal alum, Peter Thiel, has an even grander ambition: the creation of a new libertarian state outside the jurisdiction of any existing government. Through the Seasteading Institute he co-founded, he hopes to eventually build floating platform-cities out in international waters, which will either be lawless anarchy or refuges from big government, depending on who you ask. The first proposed seastead structure, a hotel dubbed "Clubstead," has yet to begin construction, despite a successful IndieGogo campaign.

Paul Allen: The human brain

Paul Allen, the lesser known Microsoft co-founder, has long been interested in how the brain and consciousness work, which has led him to fund research into how both artificial and natural intelligence. The latter endeavor is focused on the Seattle-based Allen Institute for Brain science, which is attempting to create an atlas of the human brain. Allen also owns the NFL's Seattle Seahawks, and the irony of being involved both in brain research and a sport that's come under scrutiny for traumatic brain injuries suffered by players is not lost on him.

Hardly Workin' album cover art

Andrew Mason: Hardly Workin'

Groupon founder Andrew Mason was the driving force behind his company's unorthodox culture and business practices, for good and ill, and when he was forced out in the face of declining revenue, he released an irreverent, tell-it-like-it-is letter, at the end of which he said he planned to "channel this experience into something productive." That turned out to be Hardly Workin', a self-published album of business motivational songs. Mason years ago interned with Steve Albini, founder of punk band Big Black and producer for PJ Harvey and Nirvana, and is married to folk musician Jenny Gillespie; Yahoo Music said Hardly Workin' "recalls a warmed-over Dave Matthews track."

REUTERS/Jonathan Ernst

Mark Zuckerberg: Boutique butchering

Every year Facebook founder Mark Zuckerberg engages in a self-improvement project: 2009 was for wearing ties daily, 2010 was for learning Chinese, and 2011 was for only eating animals that he had personally killed. "I think many people forget that a living being has to die for you to eat meat, so my goal revolves around not letting myself forget that and being thankful for what I have," he said. "I've learned a lot about sustainable farming and raising of animals." By 2012, though, he was buying fancy steaks from a Palo Alto market and liking Chicken McNuggets on Facebook.

REUTERS/Beck Diefenbach

Steve Jobs: Audiophilia

Not every Silicon Valley big-shot necessarily dabbles on the side, though. Steve Jobs is obviously most famous for co-founding Apple, but the two other companies he started, Pixar and NeXT, are too important to write off as side projects; the NeXTSTEP OS is the ultimate foundation for OS X and iOS, so you might say Apple is more NeXT than not these days. When Jobs wanted to kick back outside of work, he mostly listened to music, though since he was a rich man who didn't do half measures, he listened to it on $100,000 worth of stereo equipment. Digital music became a nice business for Apple too, of course, though apparently Jobs preferred vinyl.