Tricky one...
If you're using Squaredup, the Task tile could kind of do that. It would require a click to fetch and display the result and would not be "live", but it should work.
With native dashboards, the only thing I can think of would be a powershell grid widget. You would have to write a powershell script that would connect using SSH (with a ssh key so you don't need to input the credentials), run "top" and display the result.