I rolled my own. I do all my modeling in Milkshape , but I needed to add collision and physics objects to the model as well as mount points for weapons and engines etc. So I made used to joints in the milkshape format to define the mount points (by using the names of the joint to define the type of mount point) and I produced a separate model which defined the Collision and Body objects for the model (again using names to identify them). I then put this through my own optimizer/model parser and end up with a single model file (xml) of my own format which includes all the information I needed, including edge information, and optimized triangle strip groups.

I got the idea from the Torque engine over a www.garagegames.com, they use a similar technique. If I ever manage to get the time I'll release my model stuff for people to look at and use in their own projects.