I had this idea about a year ago, emailed it half a year ago, and it seems to have subsequently found its way into the circular file.
After having used 3dmice on and off for 15years or so, I feel that these are some important hardware enhancements.
3Dmice are currently great for 3D movement. With these enhancements, however, I believe they can go from great to fantastic!
Although this might not appeal to some, dismissing the idea of using anything more than subtle force on an input device, there may be many out there who might embrace the idea for its added benefits.
Here's the write-up detailing the proposed hardware enhancements http://sites.google.com/site/forceinput/