Isolate is an add-on designed to help lighting process in Blender.
It allows to "Isolate" light by turning off other lights in the scene.
Isolate is also a custom open GL interface to interact with your lights and meshlights directly in the Viewport !
Install it through the User Preferences like any other add-on
Isolation of Mesh Lights and Lamps :
select one or several lamps or meshlights, and click on the isolation button to hide any other light source in the scene, except for the world settings (AO, background). You can chose to only hide their renderability or renderability and visibility
Open GL Helper :
This button adds on the viewport an extra interface with options. This interface allows the user to see all lights and mesh lights in the scene and their state (visibility and renderability). The interface is interactive, you can ctrl+left click on the item to select/toggle visibility and renderability. You can also isolate lights from here. You can move the interface with the down header slider, or by pressing Ctrle + Alt and moving your mouse (you can disable this function through User Interface)