There are an assortment of mudprogs that I think would make a good addition to the game and allow for more versatile programming on the part of the builders. I am going to start with a few offhand that I either want to see myself, or I've springboarded from questions in builder discussions of "I wish a mobile could...."
- group_greet_prog: This prog would be a greet prog that triggers only once when a group enters the room with the prog, be it a mobile or room prog. The advantage would be not getting spammed by the same line over and over as a group goes through a quest together, also for group quests, would allow for one event trigger to advance the quest.
desc_prog: This prog would intervene between an obj/char/room's normal desc field, and instead execute the program. Useful applications would be descriptions that should change as a quest progresses. Examples being: the quest where the player casts friends on the hag, using a prog like this could literally change the desc of the mobile, subject to the onlooker. Or a room that needs to show up as crumbled and collapsed after an earthquake. These would be lines of mpechoat $n of course, but other commands and checks could trigger from the look action as well. Though most things could trigger with a exa_prog, the difference would be the interception of the actual desc of the prog holder.
kill_prog: kill_prog would be, plain and simple, the opposite of death_prog. So that when a mobile kills a player, it triggers the prog. This would make it possible for the mobile to do things like set a failure bit if the player loses the battle, or even something as simple as cackle in victory as a taunt for the rest of the party. Or, perhaps even something more sinister, like a mobile that grows more powerful as it slays victims.