Markdown is a text-to-HTML conversion tool for web writers. Markdown allows you to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid XHTML (or HTML).
Textile is a simple text markup language to be used when writing on blogs, wikis, and documents.
AsciiDoc is a text document format for writing notes, documentation, articles, books, ebooks, slideshows, web pages, man pages and blogs.
LESS extends CSS with dynamic behavior such as variables, mixins, operations and functions.
Sass is an extension of CSS3, adding nested rules, variables, mixins, selector inheritance, and more. It's translated to well-formatted, standard CSS using the command line tool or a web-framework plugin.