On a related note, I would be interested to hear what parts of your company's product you have opened.
Funny you asked. I happened to work for a startup that got acquired by a big&evil corporation that specifically prohibited our engineers not only from opening our code, but even from contributing to existing OSS projects, which, partially sparkled my original post.
BTW, there is only one item on your list that qualifies as a valid answer to my question (for obvious reasons) and that is webmin.com, which is by far my favorite YC startup.