Tomas Pettersson in Sweden is working on a new sculpting tool called Sculptris.
At it’s current stage I cannot see it replacing your main sculpting package. But using it in addition to your main sculpting package seems like a great fit for Artists.
One of my favorite features I have seen in the program so far is the ability for it to add geometry on the fly for you as you sculpt. In other sculpting programs your polygons will just stretch. But in Sculptris it will interactively add more geometry for you as you sculpt.