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.
This piece of code is a sample of how I solve a problem to merge text (or any file, for that matter) files together to one big file.
I hope you can use it, or learn from it.
ChapMaker is a new idea for working on texts like essays, articles, documentations or books. It is a simple texteditor with connection to a central database server. Different users from different locations are able to work on their projects together.