Who works like this:
do_who grabs the player's interface, and issues the who command that works with that interface.
So basically, if you're looking at changing the AFKMud interface who, make your changes to afk_who. smaug_who and dale_who are the other two.
You can find these in the following files: iafk.c, ismaug.c, and idale.c
I believe do_who was moved to interface.c as well.
I want gboards in my MUD I think. But I've always hated pre-login ANSI... The more questions I gotta answer on my way into a MUD the less likely I am to give the game a chance. But that's my personal opinion.
As for getting around in the AFKMud source... just remember that grep is your friend. I think Samson's done a nice job of organizing his code too. If you ever wanted to find flags for OLC and BUILDING, you'd look in olc.h and build.c Go figure! *kick SMAUG*