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.
Add the scripts to an Editor folder (or a subfolder of an Editor folder). To turn off individual icons, navigate to the Hierarchy Icons pane in Unity's preferences.
Last tested with Unity 2018.3 and probably compatible with most earlier versions.
The icons used are from the excellent WebHostingHub Glyphs collection (http://www.webhostinghub.com/glyphs/). They are licensed under the SIL Open Font License.