I might be writing an article about this soon: Scheme is a high level language - great for all around development, and Gambit-C can (once an application is developed in a very productive Emacs + Slime + Gambit-C environment) be used to create small and very efficient native applications. BTW, if you use an OS X or Windows installer, also get the source distribution for the examples directory.

In Unix tradition, I like to build a set of tools as command line applications, and Gambit-C is very nice for this.