A CrossCompiler is a Compiler capable of generating BinaryExecutables for a platform other than that on which it currently runs. GCC can be a CrossCompiler if correctly setup.
For example, you can compile up GCC so that it creates WIN32 executables when running on Linux, so you don't even have to go near a Windows computer during development. Coupled with a CrossPlatform GUI like wxWindows, you can use the same source code and Makefiles to create native applications for multiple platforms all from the comfort of your Linux box!
For an example of how to build and test GCC as a CrossCompiler, see 
http://kegel.com/crosstool
One page links to CrossCompiler:
