There are several community managed operating system project around that you can look at:
JOS: Java based OS. It's on SourceForge. SharpOS: C# OS (The one I am working on), the kernel is written 100% in C# (don't flame me before you actually have a look at it). Also hosted on SourceForge. There is also ONE video on YouTube. SmallTalk: Has been around for decades. Pick your favourite one.