You can find information & resources of science, biotechnology, chemistry, ecology, technology, science resources, mechanical engineering, earth sciences, astrophysics, nuclear & molecular at PortalScience.com
apfloat
High-performance arbitrary precision arithmetic package for C++ and Java.
http://www.apfloat.org/
HiPiLib - High Performance Libraries
Home of PIOLOGIE, a library for arbitrary precision arithmetic, operating on natural, integer and rational numbers.
http://www.hipilib.de/