Calculate Date for Status Change

There is no "automatic" method that I am aware of. You can manually check a field by right-clicking on it to view the cell history. Or if you have a business or enterprise account the activity log would provide you with some data as well. 

Agree with Mike.  The only workaround would be to have the status showing as a workflow, with a Date column for each status.  So instead of 1 column with the current status in a dropdown, you would have 3 columns each populated with a date (entered by someone) as they move through the workflow.   Not ideal perhaps, but you can still report off it - i.e. display all records without a date in 'Done' & 'In Process' shows the list of jobs sitting in 'To-Do'

You might even be able to show via a nested if statement calculating how long a job has been sitting at the status for.

Craig's solution works if you want to pay for a third-party application. I have Used Tony's solution of including a Date Completed column instead of a check box to indicate completion.