NOC is designed for protein structure visualizaing and analysis, for crystallographic mapping and modelling, for Gromacs/Amber MD trajectories viewing and analysis. NOC is open source project distributed with precompiled binaries for MS Windows, MacOSX, Linux/Unix. This version is the first release on CNET Download.com.
This is a pretty fantastic piece of software. The GUI is a little confusing at first but is pretty easy to get a hang of. Good integration with PDB.
Cons
Appears to have some minor stability issues with regards to mapping surface forces. Can't figure out how to map ball-and-stick with molecules that are not amino acids or downloaded from PDB. Still 5 stars.