Muhammad Yunus of Grameen Bank would be great. He started a microfinance bank and recently won a Nobel Peace prize for his work! That's not something many startups can claim. Possibly Iqbal Quadir of Grameen Phone too.
Also some European startups such as skype, last.fm, moo etc
Bob Metcalfe of 3Com
Jamie Zawinski of Lucid and Netscape
One of the Sun founders. Probably Bill Joy, but it might be neat to see Vinod Khosla's POV too.
An early employee of Microsoft. Doesn't have to be Bill Gates, but someone who was there before the IBM deal.
Some founders whose startups failed - both in the early stages, before we've ever heard of them, and those who crashed spectactularly.