On the view bug page it says "This bug is not in your list"
It would be nice to have a link for "Add bug to my list" after.
Steps to Reproduce:
The buglist is really cookie called BUGLIST= that is set by buglist.cgi when
running a query. It is a string of colon separated bug numbers. What would need
section that will basically push the current bug_id onto the end of the BUGLIST=
if it does not exist in the list.
Bugzilla 3.2 has a new tagging feature at the bottom of each page which could be used for this.