John D. Carmack: Armadillo Aerospace http://www.armadilloaerospace.com/n.x/Armadillo/Home
I'm tempted to throw in Google's Sergey Brin (Larry Page too?) for Google Glass.
And I'm sure there are a few others. Elon Musk just shows up more in the news due to his success.
Also, not all billionaires are technically inclined geeks.
It's the same reason why Bill Gates has gotten such attention for his philanthropic work. He lends something which is in a way more valuable than his money: his personal time and ability to execute.
In addition to glass, the google guys get credit for http://www.planetaryresources.com/ and the driverless cars ;)
edit: meant as reply to GP :)
ratan TATA , who pushed the low cost indian car , which is a sort of science fiction in his culture.
Idan ofer , who invested in "better place" the electric car company with the swappable batteries.
And BTW , i'm sure bezos see full e-commerce(including groceries and fashio and furniture) as a science fiction.
The link I've posted is the press release announcing him joining the company.
If he decides to pick up from a point where progress has been made, that's just less time wasted reinventing the wheel.