Script Summary: Enable all hn navigation through arrows keys and wsad.
Up and down arrow keys - up and down
W - upvote
S - flag/unflag
A - comments
D - follow link (or next page if on the 'more' link)
Highlighting color can be customized at the top of the script.
Close tabs with control + w to keep your hands on the keyboard while visiting links.
Only tested in Firefox 4.