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
Not going back to top
Seems the script won't go back to the top of the page when you move to the next page, it will stay where it currently is.
kind of annoying having to scroll back up everytime.