Here are some rather old projects, which aren't really interestung any more today, as the hardware and operating system have changed a lot... but maybe you find some useful ressources, especially if you are interested in programming i386 assembler, you'll find a whole bunch of interesting source code (dos extender, graphics and sound).

Gomez DOS Extender

Gomez Vector Engine

Gomez Music Interface

Gomez Vector Engine for C++

Other stuff