XKCD enhancer makes you XKCD browsing easier, it enables the arrow keys for navigation and show the alt texts under the image.
This extension makes your life on XKCD easier! It enabled the use of the arrow keys for navigating to the next and previous comic possible. And it displays the author notes normally viewed by hovering over the image below the image for easier viewing. If you would like more features or if you have any problems don't hesitate to contact me.