Critterding is a "Petri dish" universe in 3D that demonstrates evolving artificial life. Critters start out with completely random brains and bodies, but will automatically start evolving into something with much better survival skills.
lib_3d_mec_ginac is a library for symbolic multibody system dynamics. It can be used standalone, although it will be the kernel substitute of future version 3.0 of 3d_mec (http://www.imac.unavarra.es/3d_mec).
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.