See at a glance what components are attached to game objects in your scene with this editor extension for Unity. Icons beside each item in the Hierarchy pane make it easy to see where your cameras are, which game objects are lights, and which objects have an audio source attached. Think of it as Gizmos for the editor.
No setup is necessary after importing the files. To turn off individual icons, navigate to the Hierarchy Icons pane in Unity's preferences.
The icons used are from the excellent WebHostingHub Glyphs collection (http://www.webhostinghub.com/glyphs/). They are licensed under the SIL Open Font License.