In the next major version of Klok, I intend on adding many new features. One of those features is the ability to minimize to the system tray. You would then be able to "pause" and "restart" your current task if you get pulled away from your desk for example.
It has been a long time since I worked on a Mac, so I can't even remember if they have any equivalent feature. If so, I would like to add it and would need some help testing it. If not, I would appreciate somone with a Mac testing it out to make sure I don't inadvertantly cause a bug that isn't apparent on Windows.
If you are interested, email me at rob (at) mcgraphix (dot) com