I usually use gnuplot for visualisations, it can draw a 3d graph with colours representing the 4th dimension (splot). You can rotate the graph in a dialog, which makes it really 3d, but printing one static image usually hides some information. The usability depends on your data, though. Example showing computing time on a cluster depending on various data segmentations and task paralellisations. The darkest colour represents the optimal parameters for the given setup.