I started Helpjuice.com a couple months ago. It's now profitable.

I had an idea, called a few companies that I thought would pay for it. Then, I skipped school (I was in high school at the time) for a couple of days and built it. After I had built the BARE minimum version (now that I look back, our "search" was using simple MYSQL LIKE "search" and I was selling it) I was able to get a few companies to pay for it. And am now working on it full-time.

Maybe I'll write a blog post one day about the process.