Visit
From CFD-Wiki
VisIt is an open source (available under the BSD license) visualization system developed by the Department of Energy (DOE) Advanced Simulation and Computing Initiative (ASCI) for the visualization of large data sets. A summary of key features is available here. VisIt runs on a variety of platforms, including Linux, MacOSX, and Windows (precompiled executables are available). VisIt is an interactive system system, but can also be extended and customized using C++, Java, or Python. The system has been under development since summer 2000 and is under active development as of April 2007 (release of version 1.6)
