Since I have my taskbar display window titles ("Window list" applet, not "Grouped window list"), my laptop's taskbar can get cramped pretty quickly. KDocker lets me save space by bumping apps with just one window (ie. a unique icon) to the system tray, which has been very handy. I do wish it would "remember" the apps I place there after a restart though. (added a quick-launch to make re-traying tolerable at least)