GPP is a general-purpose preprocessor with customizable syntax, suitable for a wide range of preprocessing tasks. Its independence from any programming language makes it much more versatile than cpp, while its syntax is lighter and more flexible than that of m4. The syntax is fully customizable, which makes it possible to process text files, HTML, or source code equally efficiently in a variety of languages.
CLIP is a Clipper/XBase compatible compiler with initial support other xBase dialects. It features support for international languages and character sets. It also features OOP, a multiplatform GUI based on GTK/GTKextra, all SIX/Comix features (including hypertext indexing), SQL and ODBC drivers, a C-API for third-party developers, a few wrappers for popular libraries (such as BZIP, GZIP, GD, Crypto, and Fcgi), a multitasking client and application server based on TCP/IP sockets, object data base utilities, and a functions library.
Java+ is a Java preprocessor that adds its features to any Java compiler. It has long, multi-line strings with executable inclusions like Perl or Ruby, optionally segregates Java+ strings into ResourceBundle files, eliminates the need for JSP or ASP and their implied need for Java compilers on deployment servers (a security concern), and adds absolutely no overhead in either space or time. There are graphical and command line interfaces, and a simple, general, and recursive string syntax.
h2incn tries to directly convert C/C++ headers to Nasm-style include files, and can be used in a makefile. It is useful if you want to use the same structures or external variable declarations in C and assembler code, and you don't want to use two separate files and update both each time you change something. It is written in a mix of C and C++ code. It currently works for simple files.