In my endeavor to get bookStack included in the official Mozilla addons repository I was told to accumulate some user reviews. As a result of talking to some users I found out the upcoming version (currently in beta) of the Netscape browser, Netscape 9, has a very similar feature to the one bookStack provides.
The main difference is they use a sidebar and do not (from what I could tell, haven’t tried it myself yet) give direct access to the stored items (eg, via the bookmarks manager).
So I’m currently working toward a version of bookStack that has a sidebar so that people who want Linkpad for Firefox can get it.
It should be ready in about a week.