regexxer is a nifty GUI search/replace tool featuring Perl-style regular expressions. If you need project-wide substitution and you're tired of hacking sed command lines together, then you should definitely give regexxer a try.
NoteCase is portable (Linux, Win32) hierarchical notes manager (aka outliner) coded in C++ using GTK+ toolkit. Project is inactive as of 2008/12/09, read more at: http://factoriel.blogspot.com/2008_12_01_archive.html