Little bit of shameless self-promotion here. TL;DR note: this is for a Chrome extension only. I plan to port it to Firefox down the road.
A few weeks ago I finally started to get some free time again, and realized that my webcomic backlog could best be described as "daunting". Between intermittent wrist pains and general laziness, I just didn't want to use a mouse to click on all the various "previous" and "next" links. So I wrote an extension to let me use my keyboard's arrow keys instead.
It's free to use. Period. It's on the webstore because I wrote it to fix a problem I had, and I feel like it would be a waste of everyone's time not to share it.
If you're so inclined, you're also welcome to browse (and maybe contribute to!) the source over at https://github.com/joequincy/Webcomic-Keyboard-Navigation.
Now, I really don't have the expertise to do some crazy machine learning awesomeness, so WKN uses jQuery to seek out the "previous" and "next" links with CSS Selectors. This means that it's really easy to add the comics you read if I haven't supported them out-of-the-box. Just go to the extension's Options page, and fill in the form at the top!