Jamail Larkins, 25
Founder of Ascension Aircraft, an aviation sales, leasing, and consulting firm

"I took my first flight lesson when I was 12 and just got hooked. When I was 14, I petitioned the FAA for an exemption to fly solo before my 16th birthday. When they said no, I wrote to over 100 companies to see if they would sponsor a trip to Canada, where the age limit is lower. I had the opportunity to meet some major players, including John and Martha King from King Schools, which makes flight training products. I told them I wanted to start up my own company to help pay my flight costs. They eventually said, 'Well, you could become a distributor for us.' I started off selling instruction books and videos and grew into avionics and pilot supplies. A couple years later, I started to broker aircraft transactions and then began leasing them. To be honest, I'm not 100 percent sure how I got corporations to buy from me, because most of them knew I was 16 years old."

Bringing the Web to Life
Tristan Harris, 25
Co-founder of Apture, an online platform that helps websites add music, photos, and other media

"We had one meeting with Jim Brady, who was then the executive editor of WashingtonPost.com. Just a few days later, we received this long, involved e-mail from their head of business development. It basically said, 'We'd like to start this with our largest property.' It felt really good that a credible industry leader not only liked the technology but was serious about implementing it in a big way. In the beginning, I was concerned about how customers would view our youth. I'm younger looking -- if I completely shave, I look 18, but if I have a little stubble, I can pass for 29."

Fashion Forward
Susan Gregg Koger, 24
Co-founder of ModCloth, an online emporium featuring new and vintage clothing from more than 300 designers

"I've always loved vintage clothing. I would find stuff that didn't fit me or wasn't quite my style, but I would buy it anyway. Eric, my boyfriend at the time and now my husband, had a background in Web hosting. He said, 'You should sell some of this stuff. I can help you set up a website.' It was the summer before we went to Carnegie Mellon. We launched during winter break and had a sale our very first day. I will never, ever forget that moment -- I feel like it was my birth as an entrepreneur."

Organic Growth
Emily Olson, 25
Co-founder of Foodzie, an online marketplace for artisanal food producers and growers

"After college, I took a job as brand manager at a specialty-food store. I learned the process of getting products on the shelves and noticed it was really hard for small food producers. That was when the idea came about. Being in the food business is not as glamorous as it seems, but everyone we work with is doing it because they are very passionate. The producers get really excited about how they make their chocolates or their olive oil, and it's inspirational to know we can help them sustain their business, grow it, and continue doing what they love to do."

Playing Hard
Adam Rich, 29
Co-founder of Thrillist, an e-mail newsletter for "dudes"

"In college, we were deadly serious about hanging out. My co-founder Ben Lerer and I used to run around Philadelphia to find whatever the city had hiding in it: jazz clubs, open-mike night, whatever. No matter where we've launched, there are dudes there, and dudes need to clothe themselves, get themselves drunk, and feed themselves. That's universal. I don't care whether you are in L.A. or Atlanta or Boston; those are needs we can be serving. We approach readers the way you would talk to a college friend: 'Yo, check this out.' That intimate, friendly, trustworthy tone."

Let's Get Together
Elliott Bisnow, 24
Founder of Summit Series, a conference organizer for entrepreneurs

"My father and I founded Bisnow Media about two and a half years ago. Summit Series started because as a young company founder, I had a lot of questions, and I wanted to meet and get advice from other young founders. Now, we have a really loose interpretation of the word entrepreneur. The criteria is that it's someone at the top of his or her field who is doing something amazing, inspires people, and is fun to be around. Our goal is to create a TED or Davos, but for young people. Instead of buying Ferraris, we're working with nonprofits to leverage our resources."

The Revolution Will Be Televised
Michael Seibel, 26
CEO of Justin.tv, a live video website that draws 31 million visitors a month

"We were all just out of college, and we knew that live video was going to be big. One of our founders, Justin Kan, came up with this idea of lifecasting, and he attached a camera to his head and started broadcasting his life. That was the spark. We got on the Today show in the first month, and then we opened up the network to other people who wanted to show live video. We now have 40,000 broadcasts a day, and we show 50 million hours of video a month. We've built this great system, and we now want to power live video on other people's websites. We want to be like PayPal for live video."

Stroke of Genius
John Goscha, 25
Founder of IdeaPaint, a maker of paint that turns walls into dry-erase boards

"My freshman year at Babson, I lived in a dorm for student entrepreneurs. My friends and I would hang big sheets of paper on the wall to brainstorm. After a while, I thought, Wouldn't it be great if we could just paint the walls and write right on them? I looked around, and there wasn't a paint like that in existence, so I started developing it. I came up with a very crude prototype and painted my dorm room. The response was great. It's one of those products where people just say, 'Wow, this is really cool.' At that point, I realized this could really be a business."

These entrepreneurs are featured on our 30 Under 30 list. For trend stories, in-depth profiles, slide shows, video, and a chance to vote for your favorite, go to www.inc.com/30under30.