There needs to be a book covering social skills and interactions, from trading to diplomacy, from making friends across cultural and species lines to how to play a streetwalker. This book would be called the Companion Companion.
It will go nicely on my shelf next to the other book we need on crime, punishment, criminal investigation, court procedures, and governmental structures and functions, Law Law.
Don't confuse the Companion Companion with the SM:P book due out any time now about natural and artificial satellites, Companion Law.
Also, we could use help managing the complexities of extended family structures, marriage and courtship issues, and the subtle workings of family politics, so I'm sure we'd all buy In-Law Law.