Discovered this when some vim-like plugin failed. Realized it's about 90% of the reason I was using a vim-like plugin.
Back to vimium.
- start typing the text on a link near the icon you want to click (for this comment, `thomasa`...)
- then press Shift+Tab to highlight the previous link
Sadly, the transition to a new plugin architecture killed it and Tridactyl doesn't come even close. Some things are not possible with the new Firefox APIs, and many websites steal keyboard focus thereby ruining the Vim-like experience. Really frustrating.