OTFVis is a visualiser for Matsim scenarios. Depending on the setup of you scenario, it also works on-the-fly. To run, use OTFVis.java If you encounter any problems, make sure to read http://matsim.org/docs/extensions/otfvis.
Packages 
Package Description
org.matsim.contrib.otfvis  
org.matsim.pt.demo  
org.matsim.vis.otfvis
This package provides OTFVis, an advanced, interactive Visualizer for MATSim.
org.matsim.vis.otfvis.caching  
org.matsim.vis.otfvis.data  
org.matsim.vis.otfvis.data.fileio  
org.matsim.vis.otfvis.gui  
org.matsim.vis.otfvis.handler  
org.matsim.vis.otfvis.interfaces  
org.matsim.vis.otfvis.opengl.drawer  
org.matsim.vis.otfvis.opengl.gl  
org.matsim.vis.otfvis.opengl.layer  
org.matsim.vis.otfvis.opengl.queries  
org.matsim.vis.otfvis.utils