lhs2TeX is a literate programming tool. It is implemented as a preprocessor that generates LaTeX code from literate Haskell sources. It allows for and provides different styles for the formatting of code. You can easily select between representing operators with mathematical symbols or with ASCII approximations, as well as deciding whether or not to highlight keywords. The formatting of your own defined tokens may be adjusted. Preprocessor-style conditionals are supported, and Haskell can be used to generate parts of the document.
TclTP (pronounced "Tickle-Type") is a preprocessor based on the TCL scripting language. It allows embedding TCL command and and variable expansions in normal text. The result of expansion is inserted in the output. Quoting and escaping work in a similar way as in TCL, using braces and backslashes. A second stage of processing involves hooks defined by the document. This allows arbitrary transformations of processed text before it is written to the output. TclTP is primarily intended for generating complex static documents like Web pages. It is not a mark-up language per se. But you can define your own mark-up and use it in your documents, possibly allowing the production of output in different formats from the same source file.
The lptools suite provides a complete, programming-language independent, literate programming environment. The suite targets XML documentation, but the underlying system has no bias that would disadvantage other documentation languages. It also includes a programmable build tool (a replacement for 'make') that can handle very complex and dynamic dependency graphs.