At my age, at this stage of my career, I get to teach a completely new course.
Last year, my business school adopted a new course requirement, a course in American economic/business history. We had two reasons for this. First, in light of the recent business cycle events, we thought that our students could use some historical precedent on things. And second (here's where the inter-program politics comes in), my university now requires a course in "historical or cultural studies" as a part of its general education requirements. I would generally have been willing to leave that to the history department, but, at this point, we have essentially no one who can teach what would be for us a relevant American history course. (The full-time history faculty includes four faculty members, with the following areas of research and teaching interests: China/Japan; medeival Europe; 20th century Europe (especially France), and 20th century American political history. No one who even has any coursework, let alone interest in, economic history.)
So I wound up with it. I do, at least, have a graduate field in US economic history (but that was nearly 40 years ago), and I have always been (and remain) very interested in economic history. I've never taught a course in economic history, and my research interests (urban economic development/policy; labor markets; economics of professional sports) are elsewhere.
The course itself is an entry-level course, aimed at first-year students, and has no prerequisites (not even intro econ...not even having taken high school econ). (When we were talking about doing this, I had assumed that it was going to be a junior/senior level course, with the intro econ sequence as a prerequisite, and drawing mostly students who had completed a fair amount of the business core. Silly me. And I had to miss the faculty meeting at which the course was adopted.)
But I'm having a great deal of fun so far (two weeks worth of classes), and I'm trying to pull in enough economics so that some of the factual material in the text (History of the American Economy, by Gary Walton and Hugh Rockoff) has more theoretical context than the book gives it.
Given that I plan to retire in May 2012, however, my program will have to be very careful when it begins to look at replacing me. Neither of the other two economists we currently have would have a prayer in hell of teaching this course. They don't have the academic background, and neither of them grew up with US history, let alone US economic history, in the foreground of what they did. Fortunately, finding someone who can teach it shouldn't be all that hard. In the meantime, I get to have some late-career fun.