At the end of a presentation or on-stage discussion, there is always that moment of lost time and dead air when the moderator fumbles with her paper and searches the audience for a microphone, before taking questions from attendees. 

But at the discussion that opened this week's Fast Company Innovation Festival, Fast Company's executive editor Noah Robischon took that awkward moment and filled it with a question he'd asked the founders and executives on stage to prepare ahead of time: 

What great big business opportunity--one totally separately from their current company--was on their mind?

Here's how a few responded.

"I'm still a closet science nerd. I think there's a massive opportunity to use data to improve health outcomes."
--Dave Gilboa, co-founder and co-CEO of Warby Parker

"Transportation. The world around us is changing really rapidly. Why aren't our old transportation systems keeping up?"
--Katia Beauchamp, co-founder and CEO of Birchbox

"You want to look at the things that everyone else thinks are bad ideas. If everyone thinks it's a good idea, there's probably lots of other people are trying to do. Do instead something you and only you do best."
--Tristan Walker, founder and CEO of Walker & Co.

"Create intimate experiences by connecting large groups of people."
--Chad Dickerson, CEO of Etsy (We can presume he's taking some inspiration from the success of Etsy Teams, the hundreds of self-organized groups of sellers--often by geography or interest--around the globe.)

"I don't think we've ever been in a period [of time] where higher education costs so much, but prepares people so little for the world after college. Education needs to become more flexible and nimble."
--Neil Blumenthal, co-founder and co-CEO of Warby Parker