I like ignore functionality. You can't get rid of all the jerks, and this situation will certainly arise again. One good thing about ignoring a jerk is that they can't /msg you 500 times, which I would think would be a pain for someone to check all those to remove them.
Actually, is there a limit of /msg's you can have on your screen at once? With people now remotely using the chatterbox (or with a quick LWP script) someone could easily send hundreds of messages to every user they can get the name from (like the list of users in 'Saints in our Book'. I would consider a threshold of showing up to maybe 10, and the rest would be waiting for the user to clear what they have. When they have the 10 being shown, there could be a 'X more messages waiting' note, so the user knows to clear things up. Anyways, could help prevent the scenario I mentioned.