I'm not exactly sure what you are asking for.  PCS makes a 1500W and a 2400W dimmer that are much larger and fit into 2 gang junction boxes.  They are quite expensive, but handle larger loads.  There are a couple of new vendors making 50 Hz dimmers for the European market that have a squarish form factor (not sure they are available just yet).  But, they won't work in the US.
Can you elaborate in more detail on what you are wanting?