The couple donates $1 million to support a Washington state initiative that would require criminal background checks on firearm sales at gun shows and online.
Genetically modified bananas loaded with vitamin A are scheduled to go into human trials in the US with the aim of improving nutrition in Africa.
Facebook CEO Mark Zuckerberg saw the biggest jump in wealth among all the people on the list, earning him the No. 11 spot.
Stock sale puts Gates in second, behind fellow former CEO Steve Ballmer.
For the first time in four years, Microsoft's chairman beats out telecom mogul Carlos Slim. Other tech execs grace the list this year, including Ellison, Page, Bezos, Zuckerberg, and some newcomers.
Gates has granted Manchester University £62,000 to research making condoms out of a new material.
It seems that the Microsoft chairman would like Facebook and Google billionaires to pay attention to eliminating diseases afflicting the poor, in addition to wiring up the planet.
In his foundation's annual letter, Gates says it's a myth that poorer countries cannot become wealthier.
Ballmer gets the blame for Microsoft's recent lackluster stock performance and assorted product misses, and so should Bill Gates and rest of the company's board of directors.
In a new interview with Rolling Stone, Microsoft founder Bill Gates dropped a few tech tidbits, including that Microsoft "was willing to buy" WhatsApp. He's also no Edward Snowden fan (no surprise).