It would be nice if there was a customizable light, like there is a custom playertype. You would be able to change the color of it, change how bright it is, change the transparency of the light (so it's an ambient light or an actual light (like player light)), change how far the light reaches, change in which direction the light goes, change the effect of the light (blinking or multiple colors like RGB), and change the speed of the effects.
It would also be cool if you could do all that^, save and name the light you made, and then add it to your collection of lights somehow.