You can already set to Hidden, Friends-only, or Public by clicking on "Change Visibility" on the upper right of your mod page. There's no current option for Unlisted (visible to anyone who has a direct link), but that seems like a useful thing to consider.
Yeah but what if I have 8 random people on the forum that need to see it for some reason. I don't want to add them all to my friends list, and therefor also allow all my other random friends to see the file. An Unlisted option or a 'enter priveledged user ID' type thing is what I'm going for.
Will anything be done regarding the Save features? By this I mean, There is no "Save As" function. This prevents updates to the same .esp files to be saved as a seperate, optional .esp.
If you load an ESP without making it the active file, when you save it will ask you for a new name and you can save it as an extension to the other esp, though it wont require it so be careful with this. (Make sure the person knows you need both, etc)