Kay language - arbitrary precision decimal number library and examples.
The decNumber functionality is linked by my Kay (aka y3c) compiler as part of its standard library. The library is written in C and is available here: http://speleotrove.com The documentation is available here: http://speleotrove.com/decimal/decnumber.pdf
I did not want to or plan to implement FPU instruction set support any time soon so this library comes in handy.