You are saying that you only have code which is entirely private. This is most likely code you wrote for your employeer, which you can't show me anyway because chances are that it is NDA private. Or, you have code which you wrote for say, an iPhone app which you are probably never going to show to anyone. That is all fine.
However, you are also telling me that you've never integrated any open source projects into your code or relied on any non-commercial external libraries. Or, maybe you have done that.
But then I have to wonder why you've never contributed back to any of these projects that you've depended on. If you are a great dev, I'm sure you found them lacking in some way and wanted to contribute a bit back to them.
Thus, we've come full circle. Any developer that I would want to hire, has figured out that there is a massive ecosystem of open source projects out there. They are integrating them and contributing something back to them. They are drawn to these projects like flys to sh*t. These projects teach them new tricks because they are studying others code. They are drawn to give back to these projects because they are taking so much good from them. That is what makes a good developer in my eyes.
Here is a really good case in point example. Last night I was working with the amazing Underscore.js library, which I'm fairly new to. I found that I wanted to do something with it, couldn't figure it out and made a suggestion on how to improve it [1]. Someone from the community responded quickly, we had a bit of really positive back and forth and in the end I learned something new about the library. I expect that anyone I hire has the gumption to also be doing similar work.
Go fork some projects.