Shabbat 18: "Set It and Forget It" - A Daf of Modern Shabbat Issues
A new mishnah, a new machloket between Beit Hillel and Beit Shammai: beginning a process before shabbat that continues into shabbat, with no new involvement on your part. Namely letting your tools and vessels rest on shabbat. Plus: the concept of a "shabbos clock" (timer). And the concept of mar'it ayin (the appearance gives the wrong impression). Also, the beginning of the conversation of Jew/non-Jew interactions when it comes to shabbat.