Sleazy Fork is available in English.
Can work on almost any webcomic/manga page, preloads 5 or more pages ahead (or behind), navigates via ajax for instant-page-change, lets you use the keyboard, remembers your progress, and it's relatively easy to add new sites
Development has stalled, I made a fork
Hello everyone,
It seems like Amibode has stopped developing this script. There has not been an update since March 2015, and he is not answering to e-mails. Because of this, I decided to fork the script and take over development. I have fixed most of the issues reported on GitHub and OpenUserJS, and I'll go through the ones here soon.
My fork is available on GitHub, OpenUserJS and here on Greasy Fork. Please report any issues and suggestions on the GitHub Issue Tracker.