Neon lights using stained glass and glow squid ink sacks.

Right clicking a block of stained glass with a glow squid ink sack will make it glow and emit light. This could also be combined with redstone in a crafting table to make neon lamp blocks that can be powered using a redstone signal. A simple addition such as this would add an incredible variety of uses into the game and be a really unique and pretty way to illuminate parts of your world and builds.