A simple way to create a syntax highlighting editor for a custom language/grammar and/or create custom grammar parsers. This is a .NET project written in C#. See details here: http://acct001.com/wordpress/?p=190
Simple text editor for editing multiple language files in parallel. Corresponding translations are automatically highlighted in order to aid reviewing against multiple sources. Supports gettext PO and key = value format. Highly recommended for polyglots.
SrcComDoc allows documentation written in source comment rows to be extracted, formatted and highlighted according to the chosen documentation format. The basic SrcComDoc syntax is source and documentation language independent.