Today, I released the source code for a few of my older projects.
You can do pretty much whatever you want with them, but I put them under Creative Commons BY-NC-SA, which means two things:
1. You must give credit if you use anything significant from them.
2. You can't use them commercially.
It also says you have to release them under a similar license, in hopes that anything based off of these will be open source, but I don't want to force that, just want to encourage it, which is why I went with Creative Commons and not something similar to GPL. Creative Commons just says it has to be released under a license that allows use of the content in some manner, but it isn't specifically a software license so it doesn't require you to open source it. But at the same time, it can't be released commercially, so yeah.
You can find them here: Anotherdayanotherga.me
Have fun. :)