A probabilistic, flexible, and compact 3D mapping library for robotic systems. OctoMap provides efficient occupancy grid mapping in 3D using octrees. OctoMap development has moved to http://octomap.github.com/
MBDyn_sim_suite is a collection of free pre&post-processing tools and simulation models for the open-source multi-body analysis software MBDyn forming a general purpose simulation environment for structural dynamics with an emphasis on wind turbines.
Erode is a comprehensive layer over ODE (Open Dynamics Engine) library which allow you to easily create ODE world and visualize them (through Qt widget). It also offers convenient functions to control the appearance, parameters etc.