Github is pretty advanced in project-sharing but it's also technic, not usable by everybody.
OpenBuilds is intresting because we can follow a from scratch project at 100% but the idea is to share what you're doing and then get some comments and/or help to get it done. People don't really take part to the project as you would like to do @Sander
So I discovered Artella by this topic and can't say much but this kind of UI is great, it seems to be easy to use and so easier for people trying to make a collaborative project. It's smooth, clear and easy to handle. You project could be more "hilighted" on this kind of platform.
I don't know HITRECORD, I'm gonna shut up on this one.