jknav is a simple vi-link j/k navigation and link hinting extension for Chrome and Firefox.
After the plugin is installed, use 'j' and 'k' to scroll page down and up.
Use 'f' to highlight links, then type a number corresponding to the link you want to follow. If your number is too short (e.g. there is link '2', '21', '22', ... and you want to follow the link '2') - press ENTER to confirm your choice.
In the root there is a
jknav.js file, which is the main plugin code and two
folders - for chrome and for firefox. There is also a shell script to build
If you want to develop plugins and modify code - copy the jknav.js (or use symlinks)
It's a free software, distributed under MIT license.