HandyTorch

Put a torch or glowstone (or lavabucket) in your hand, and you'll shine through the darkness as you walk around.

To use:

(1)  Equip a torch, glowstone, or other light-emitting item in hand.

(2)  That's it.  No configuration, no permissions, no commands.

Caveats:

There is a minor Minecraft bug in areas of sky-lit water at night.  When a light is extinguished, it can leave some glow in the water until another light is presented nearby.

This version does not try to compute overlap of light sources.  There may be some cases where it acts funny if two people are on the same block, lighting and extinguishing their own lights.

This is an adaptation (and resurrection) of a couple of older dynamic lighting plugins.  Most have been discontinued.  I've rewritten the code from scratch, after seeing how they fooled CraftBukkit and Minecraft into introducing a light in the world at the player's location.