Forget classic Beatles songs, Take That's comeback hit and the Party Shuffle playlist. The latest chart-topper on the digital music download website iTunes is a series of lectures on Kant's epistemology by a senior lecturer at Glasgow University.
Susan Stuart is bewildered by her star status, which has won her fan mail from students across the globe and requests for notes and handouts.
"I don't understand it. It's bizarre as far as I'm concerned," she said.
It was only last year that Dr Stuart began to record her lectures with a lapel mike for the benefit of students with disabilities in her senior honours class.
Joe Maguire, a computer science MSc student, put them on a web page as a podcast for local use, but he recently suggested putting the lecture series in the iTunes education section.
Dr Stuart instantly soared to first place, overtaking podcasts from academics at the University of California, Berkeley, and Harvard and Edinburgh universities. Although she dropped out of the top slot after more than a week, she has remained in the top three.
The number of students taking Glasgow's course on Kant has more than trebled despite Dr Stuart's warning that it would be tough. But she finds that the students need less help now that they can go over the podcasts as often as they want.
Earlier this year, Dr Stuart won a teaching excellence award from Glasgow for her innovative teaching. Some of her tactics included using an electronic voting system in logic lectures and teaching students to structure essays by setting up web pages.
"I'm giving lectures with same passion and excitement I give every year: more, because I'm finding out more about Kant."
The podcasts can be accessed at http:///podlearn.arts.gla.ac.uk/kant/index.html