Mac OS X only: Have you ever been busy getting something done when the dock icon starts bouncing up and down? The Switching To Mac blog writes up the process of completely disabling that effect.
The process is usually simple enough—just uncheck the option for "Animate opening applications" in the Dock preferences—but some applications start bouncing anytime they think they deserve your attention, breaking your concentration on whatever you are busy doing. The Switching To Mac guide explains how to use a terminal command to disable the bouncing entirely.
Readers will probably note that if you really want to concentrate, you can always close your IM application or use a full-screen, distraction-free environment like Writeroom, but it's a useful tip if neither of those options are available for you.
Hit the link for the full walk-through, or learn howblock internet distractionsfor some distraction-free working time.
How to permanently stop Dock icons from bouncing [Switching To Mac]