If I had to pick a favorite course for PSTS it would probably be Ethics & Technology. The first ethics course was all about learning the fundamentals of how ethics is done. What will you take as your measure of morality? Anyone can intuitively judge for themselves what they find acceptable or not, but working with ethical frameworks prompts many new questions to consider, making their use both interesting and useful. The second ethics course went more in-depth regarding various fields of study (e.g. robot ethics, bioethics). It showed the various challenges that come along with new and emerging technologies. It was especially interesting to learn how seemingly basic, innocent technologies (e.g. running water) can utterly disrupt the social communities of entire cities (running water inside the house made it unnecessary to go to the local water well—the epicenter of most social activity).
Most of the grades for these courses came from essays. You could basically write about anything you liked, as long as it described any technology and its (potential) ethical ramifications. Having the freedom to pick just about anything you like as an essay topic is present throughout most PSTS courses, thankfully, and it has been quite motivating for me. This freedom allowed me to pick topics that interested me and therefore made it that much easier to start writing on them. It also allowed some of my fellow students to write about one technology they are very interested in (e.g. brain imaging) and just use the various courses to discuss this technology from a different viewpoint.
Apart from the content, another big aspect of what makes a course fun is the teacher. The first course was almost entirely taught by a high-octane philosopher that provided all the required energy to make it through four hours of class. The second course was taught partly by the aforementioned teacher as well as various experts teaching about the ethical issues within their own field (e.g. nanoethics). This made for a lot of variation and quite some detailed presentations about niche areas. All in all, the Ethics & Technology courses just had a lot of interesting stuff to offer, had engaging lectures, and gave you every opportunity to customize the courses to your own likes and interests.