Release some of your own code.

I can’t stress this enough. If you don’t have code on github (or google code or your own site or whatever) you’re wasting a big opportunity. Releasing your own code allows me, a potential employer, to know your capabilities before I hire you. This stuff gets people interested in you. If you release a lot of your code, you may even get others to help you maintain and grow it. This is how open source projects get going. I almost consider it a red flag to see a resume without a url to github or something similar.
Blog about it.

Write down everything you learn as you learn it on your blog. Next thing you know, 3 years have gone by and you have this huge body of work. Stuff on your site draws the attention of other developers who are struggling with similar problems. You become an expert without really meaning to. If you blog constantly about what you are doing, what you are studying, you’ll find that people come to you with work to be done expecting that you are awesome because, well, you’re explaining all this stuff to them. I can’t stress the value of this enough, though it is very time consuming. This is especially valuable if you’re a freelancer.
Build something interesting.

I once spent a month or two writing a photo gallery in PHP just to have an excuse to learn PHP better. I learned Smarty with that little project, too. I’ve built a lot of things for the excuse to learn it. I built with a friend and we chose Ruby on Rails mostly because neither of us had built anything with it and wanted to learn it. Forcing yourself to do things with new languages and environments will grow your skills faster than anything. Don’t rely on the skills you have; always look for chances, excuses really, to do things in new ways. Working with emerging technologies will make you debug that technology itself and maybe contribute fixes back to it. It can be painful, but it also makes you really learn how that technology works.