At several places I've worked, AIM is a vital part of office communication. It's usually considered somewhere between email and a phone call in terms of response time and disruption. With any medium of communication, however, there are polite ways to communicate, and, well, impolite ways as well.
One particularly disruptive habit of certain people is what I call "rapid-fire AIMing"
(since then I've also heard of people referring to it as diarrhea of
the fingers, haha). It's when someone sends you many partially-thought out or
incomplete messages in succession, causing you to be constantly interrupted to the point
where you can no longer work on whatever you're doing, but end up having to pay full
attention to each line as they drift in--until, at last, the sender's thoughts or request
has finally achieved a level of coherence to enable a response.
Something like this, a contrived example I sent in frustration to a friend after one
Please don't be a rapid-fire aimer. Take a moment to collect your thoughts into a
reasonably coherent statement or question before aiming someone. Thank you.