Japheth's assembler, JWasm
JWasm is a free MASM-compatible assembler with these features: native support for output formats Intel OMF, MS Coff (32/64-bit), Elf (32/64-bit), Binary, Windows PE (32/64-bit) and DOS MZ. precompiled JWasm binaries are available for DOS, Windows and Linux. For OS/2 and FreeBSD, makefiles are supplied. Instructions up to AVX are supported. JWasm is written in C. The source is portable and has successfully been tested with Open Watcom, MS VC, GCC and more. As far as programming for MS Windows is concerned, JWasm can be used with both WinInc (32/64-bit) and Masm32 (32-bit). Since v2.01, it will also work with Sven B. Schreiber's ancient WALK32. C header files can be converted to include files for JWasm with h2incX. JWasm's source code is released under the Sybase Open Watcom Public License, which allows free commercial and non-commercial use. There's a bunch of source samples available - they are supplied with the precompiled binary packages.
CGUI - a gui lib for multiplatform
This is a group of makefile scripts and templates that helps the developer and end-user to configure, update, and build Allegro/AllegroGL/etc projects, on many platforms, and with different compilers, in a easy way (just type "make" and it will work).
CBAR - a bar code reader lib
CCOM - a lib for serial port interface
CPRI - a lib with an API in C for easy printing of reports to printer or html. Multiple platforms. Based on CGUI and Allegro.