Enhancer for YouTube - Tons of features to improve your user experience on YouTube™!
GIFit! - Quickly turn YouTube videos into GIFs (chrome extension)
Iridium by ParticleCore - Iridium is an extension built to improve the user experience on the new YouTube Material layout.
Youtube Plus - Home of the extension YouTube Plus that allows you to experience more on YouTube - ParticleCore/Particle
Magic Actions for YouTube - Magic Actions is an extension that changes the way you’ll watch videos on YouTube.
Turn Off the Lights - With a single click on the lamp button, the page will fade to dark.