Tecplot 360!

ParaView is an open-source, multi-platform application designed to visualize data sets of size varying from small to very large.

VisIt is an Open Source, interactive, scalable, visualization, animation and analysis tool. From Unix, Windows or Mac workstations, users can interactively visualize and analyze data ranging in scale from small (<10^1 core) desktop-sized projects to large (>10^5 core) leadership-class computing facility simulation campaigns.