Due to recent problems with one of my scripts I was going to create interface to allow some trusted users (or any user with more than 1000 edits except some blacklisted) to _stop_ any of my bots without blocking bot's account. Of course, such a tool should check which user is making this request; now the only way to do that is to ask password on Wikipedia.
You could allow stopping from irc to any with a wikipedia/ or wikimedia/ mask. I'm sure a wikipedian with mask can be easily found on irc. However this restrict by irc "affiction". Some other bots use posting on their talk page to be stopped (on detecting the "You have new messages"). But this would allow to stop it to anybody...