I was having problems getting VS 2005 to reference the UnityEditor namespace even when I was putting the script in the Assets/Editor folder. That's when I went looking to see if there was a UnityEditor.dll file I needed to add as a reference. When I opened the Unity folder in my Applications, I think I'm missing some stuff. My Unity.app folder seems to be missing. Unity runs fine, I'm wondering if they are hidden or something. I used to be able to see it, I know that for a fact. Can anyone shed some light on this?