I found IM reference *very* frustrating. The patrons -- usually 18-22 year olds who are comfortable with 20 AIM window -- would happily wander off in the middle of something while I was asking them questions. Frequently a reference interview would take longer than my shift, and the user wouldn't be around for me to explain that someone new was coming in. And yet all while I was monitoring the window for new IMs, my number one priority was supposed to be manning the desk and being alert for physically present patrons, followed by phone reference. It was enough to drive a girl mad.