If you haven't yet made the time to join our Sunday morning chabura, led by R' Yechezkel Rosenberg on the Seventh Perek of Berachos, you might want to give it a try. It is one of the best programs we have ever run and you are sure to be challenged.
R' Yechezkel usually gives a brief summary with the sources at beginning of the session and a short shiur covering what we learned at the end. Here are the mp3 audio files for the beginning and ending shiurim from last week (3/27/2005) on the subject of what happens if one or two people what to leave and make a zimun.
