RTextDoc

"A complete editor for structured text documents with proofreading features. RTextDoc is designed for typesetting professional research papers using LaTeX that are heavy on mathematics and images. In addition, it is designed for writing notes, books, ebooks, slideshows, web pages, man pages and blogs using AsciiDoc mark-up language. RTextDoc also supports DocBook.
What is special about RTextDoc compared to other text editors?

• Support for LaTeX and AsciiDoc plain-text mark-up languages
• The only LaTeX /AsciiDoc/DocBook editor with instant grammar checker for >20 languages
• On-the-fly spelling for >20 languages
• Dozens of integrated dictionaries for off-line usage.
• WYSIWYG equation editor and built-in BibTeX database manager
• LaTeX to HTML and HTML to LaTeX converters for very basic texts with equations
• Build-in PDF viewer
• No installation. Fully portable. One can carry RTextDoc on a USB flash drive
• Simple LaTeX texts with equations can be previewed without LaTeX installation

All such features in one product make the program unique among other editors. Since it is based on the RText editor, it is a complete source code editor for dozens of programming languages with syntax highlighting and code folding."

http://jwork.org/rtextdoc/