- You know jQuery and can mockup things easily. Mocking things up with an eye towards usability is a great skill.
- You can make wireframes fairly fast, in OmniGraffle or Dreamweaver. You have something to show.
- You have designed and run usability tests yourself. At least a few times. (You can easily learn this and just practice it yourself.) This is a biggie.
- You've created an open source UI element in jQUery. (For example, a dropdown that lets you also add items to it, or a multi-part button, or something like that). You've written up the tech process and the user experience aspects of it.
- You're familiar with UX design patterns (Yahoo's are a good start, search for them), and you've written a critique of them.
If you have a few of the above, you're doing great. And things to show. For example, when I was a programmer and starting out in UX, I wrote a script to test 2 versions of a footer for a webpage, wrote up some theory around how they might differ and why in actual usage, and then measured the actual usage. (That was in 2001).
Show an interest, and show that you've done stuff.