GUM Small, unobtrusive and just the perfect way to keep track of UTC - if that's what you need to do.
The best things in life are the simple and elegant ... and often free. (Version 1.3.2)
KALKI This little utility is EXCELLENT! The best way that I've found to keep track of UTC. I have other clock utilities set to various time zones to keep track of friends, but this is the neatest of them all. (Version 1.3b1)