In Mac OS X, you vote with your Dock.

I have totally supplanted the Dock's "Keep In Dock" feature with LaunchBar. When I login for the first time, my dock contains the Finder and the Trash. It accurately reflects my running applications, and never shows anything I'm not running at right then.

This is slightly unfriendlier to strangers, but works out beautifully for me. I've pinned it to the left side, bottom, where it's out of the way unless I attack it -- and I *rarely* trip over the dock by accident, in this position.