Rated 4 out of 5 stars
Useful, but has some bugs.
Eg: can't have a space in the regexp, otherwise entries will be messed up (can be corrected by editing directly in about:config).
NB: using %20 might be a good workaround if you need to use the space character, eg:
[&?]q=is\%3Astarred\%20([^&]+) will work to recognize keywords from a google bookmarks search url, eg: