One of my favorite features of Mozilla, for several years now, has been custom keywords which allows users to name bookmarks for faster access. I, for example, have named my bookmark for mozillaZine.org "mz" and typing "mz" into the address field takes me to that bookmark location. A second, and lesser known, feature of of Mozilla's bookmark handling is the
%s wildcard flag. Users can use
%s as a variable in URLs and when combined with custom keywords it becomes a very powerful tool.
A good example of this is for searching like at Bugzilla or Google. I have the bookmark
http://bugzilla.mozilla.org/show_bug.cgi?id=%s which I've given the keyword "bug". Now typing something like "bug 12345" in the address field is interpreted like this: the "bug" keyword gets resolved as the bookmarked URL
http://bugzilla.mozilla.org/show_bug.cgi?id=%s and then the
%s variable gets replaced with "12345" yielding the new URL
http://bugzilla.mozilla.org/show_bug.cgi?id=12345 which loads up the bug I was looking for. A similar example is my custom keyworded Google bookmark. The bookmark is
http://www.google.com/search?q=%s&btnG=Google+Search and my custom keyword is "g". Typing "g foopy" does a Google search on the word "foopy".
update:I really should also point out that these features can go a lot further than what I've suggested here in this post. Check out grayrest's page on Mozilla bookmarks to see some more of this powerful feature.