Avi K – excellent idea. For instance, check out Zelig Pliskin’s “Love Your Neighbor” which goes through the parshiot giving all the mitzvos bein adam l’chaveiro in each parsha with all the details, suggestions and illustrations. An “oldie but goodie.” I learn it almost every Shabbos.
Another good one is R’ Shaul Wagshal zaztal’s “Derech Eretz: A Torah guide to proper behavior in everyday life,” which has just been reissued by his sons in pocket format.
Also, R’ Ephraim Zaitchik’s “Sparks of Mussar,” also in pocket format, which gives principles and incidents from the lives of the Mussar greats starting with Reb Israel Salanter through the Chofetz Chaim.
I’m not acquainted with Chassidic sources, but perhaps someone else can list a few of those.
Anyone else with sources? It’s the Three Weeks, and time for taking stock of those particular mitzvos.