[ excerpt from developer's www site ]

Jam is a small open-source build tool that can be used as a replacement
for Make. Even though Jam is a lot simpler to use than Make, it is
far more powerful and easy to master. It already works on a large
variety of platforms (Unix, Windows, OS/2, VMS, MacOS, BeOS, etc..),
it is trivial to port, and its design is sufficiently clear to allow
any average programmer to extend it with advanced features at will.

The main differences between Jam and Make are the following:

- Jam uses "Jamfiles" instead of "Makefiles".
- Jamfiles do not normally contain toolset-specific rules or actions.
  They're thus portable among distinct compilers
- Jamfiles are a lot simpler than Makefiles to write and understand,
  while providing the same functionality, and much, much more !!

WWW: http://freetype.sourceforge.net/jam/