I encourage you to post your work.
If anything, maybe make a snippet out of it for the AFKMud Snippets.
As for anyone else interested, a saveall need only loop through the characters, and invoke do_save on them. Example (may not compile... didn't test):
CMDF do_saveall( CHAR_DATA *ch, char *argument )
CHAR_DATA *vch = NULL;
send_to_char( "&[immortal]Saving all players...\n", ch );
for( vch = first_char; vch; vch = vch->next )
if( !IS_NPC( vch ) )
ch_printf( vch, "&[immortal]%s commands you to record your progress...\n", ch->name );
do_save( vch, "" );
You could do a few other things in there... like IS_IMMORTAL(vch) && if they have a building area && if it is loaded, then do_savearea( vch, "" );
Not too hard really.