you can also see an endless related thread on [wp-hackers] Re: Blogroll, Bookmarks, Links?
I’d say something like: “Add/[book]Mark/Save this topic as your watched thread/to the list of your watched threads”.
OT: what are reasons/purpose of:
'name' => __('Key Master'),
'capabilities' => array(
'edit_others_favorites' => true,
is it ethical?