The highest paying specialties in academia are generally the same as private practice, ie radiology>surgery>medicine generally. Of course chairpeople get paid more, I think that the avg salary for chairpersons of different departments is usually 200-400K, with medicine chairpeople earning 300K at my school (much more then your avg internist). They really do reward advancement in academia, more so then I think that they do in private practice. On avg, I've heard that you can knock off ~20-40% of the avg salaries that you see of private practice physicians to come up with an avg salary of an academic physician, depending on his or her activities (eg, in terms of generating income, tesitfying in malpractice cases>clinical work>research).