Another approach is to store the computed 2D or 3D coordinates (that you would normally view with snapplot in a special format, and use an interactive 3D viewer for this.
The first step would be to create that intermediate format. Depending on the viewer, and different format (or program) needs to be selected to do this. We have currently two programs available: snap3dv: writes a number of formats, all intended for exported outside of the NEMO environment (typically they are all ascii files), and snapxyz: writes an xyzc file (a regular NEMO structured file which you can view with tsf).
As for the different ascii format, see the comments in the manual page of snap3dv which programs can be used.
As for the xyzc format: the program xyzview can be used to interactively view any 3D coordinates of a snapshot at different times. In addition, one can also store a 3D vector information to the 3D coordinates (could be velocity, or force field or magnetic field direction) of a point, and display these. xyzview can keep a limited number of point data in memory, and display them in rapid succession, in the view/zoom/velocity mode that can be changed dynamically. The viewing conditions can be stored in a file, which could be used to create offline movies in a mode described above.
xgobi is is versatile multi-variate data browsing and analysis tool which suits itself quite well to some interactive 3D viewing of N-body data.
snapprint in=snap.out times=10 | xgobi
You will need to obtain xgobi via independant means, it does not come with NEMO. A new version of xgobi is under development, see http://www.ggobi.org/.