In my case, I'm not even allowed to show my code, because it belongs to my company, so that's not an option at all for me. However, the following could be:
Indicate your years experience
This does not necessarily say something about your coding skills, but it does say something about management, decision making skills, ability to work with other people, etcetera.
Show the projects you've worked on, and your role in them
You can show some of the projects you've participated in and say what your role was in those projects. You might not be able to show the code, but you can explain that "I did this like this, so that it's futureproof" or "I did some research and found that method X, which I implemented, was the best for the case".
This does not show actual code, but it does show a bit of your train of thought.
Talk about your skills
I like speed in websites, so I could make a section on my approaches to achieving that. You can think of two or three things you are good at, and then use that to start a paragraph ( like this one ;) ) about something that you know a fair amount about. Don't forget to add examples (e.g. "speed: check out the speed of the flow in example.com").
Sharing code you've made (but isn't yours)
We all have that piece of code, shining in its brilliance, that we'd like to share. You MUST ask your employer*, otherwise it might result in nasty nasty situations.
An option to make it less 'stealable' is to take a screenshot of it and post that, or only show it upon request.
Don't forget, you don't have to show everything, just some smart/good functions should do.
* "Even if you're self employed, the code may not necessarily belong to you - e.g. if you're contracting/consulting." - Jon Story
Certificates or diplomas
If you have any, obviously, add them. This, again, might not really reflect your actual code, but it does help paint a picture of your overall skillset.