3D Mouse or Spacemouse
I have never used it. But it looks like something I will buy very soon. After watching a few review videos seems like a no brainer.
The coolest thing about it is that you can use different 3D software packages and navigate exactly the same way in all of them!
Link to the copmany that sells them:
Link to a youtube review:
PS. I am not associated with them in any shape or form :)