Rig Studio tool is out and in few days, after moderation, will be available from highend3d.com.
Difference from other similar tools what modules in here is a maya scene. And user can adjust them, and easy create new custom modules.
This system not limited a count of modules, but use many types of them. For example foot module can be simple or advanced, and its for every part of the character.
Now RS have basic modules what can be using for building many types of characters, but later will be many modules what will be expand this ability.
More information in RS System page.