If you say "This is something I built in my free time", or "This is something I built while I was learning Backbone" (and keep you tone enthusiastic, not apologetic), then people will understand the context in which they should be judging what they see. If they're smart, they'll realize that seeing what you can do when you don't have much time, or when you're on unfamiliar ground, is at least as valuable as seeing what you can do under ideal conditions. If they're not smart, do you want to work for them?

That's a good point and it's what I've been following so far. "Here's a project I built in my free time because I wanted to brush up on my Python skills, and in the process I also learned a lot about Flask, MongoDB, HTML5, CSS, and JavaScript."

That's hard too. It might help if you can come armed with some benefits of releasing something as open source, like the fact that other people will be able to find and fix bugs for your employer, which is basically free labor.

Also a good point. I'll have to give that a try.