jk scroll от h43z

j => scroll down
k => scroll up
h => go back one page in history
l => go forward one page in history
t => reopen last closed tab
w => close tab
Escape or CTRL-c => remove focus from active element
G => go to bottom of page
gg => go to top of page
r => reload tab
i => focus next Input element
w => close tab
t => reopen last closed tab

https://github.com/h43z/jkscroll

works good with this extension https://addons.mozilla.org/en-US/firefox/addon/click-on-selection-with-enter/