TimeLeft lets you count down to an event
I was recently playing around with Windows Gadgets, trying to find a decent clock gadget for multiple timezones. Selection was pretty grim, and I ended up settling for an okay-looking gadget, just because I was sick and tired of searching. Then, I was reminded of TimeLeft; it's a true classic. It's one of those modest utilities that has been around pretty much forever (check out the Windows XP wallpaper on their screenshot), but is incredibly diverse for what it does.
It lets you count down to specific events, even if said event is months away (such as when you'll next get to see your long-distance girlfriend ... just saying). It also works as a stopwatch and can be used as a clock with multiple time zones. As for skins, it's skinnable via Winamp skins. The fact that it can pull fonts and colors from an existing library of a gazillion skins written for another application is pretty clever in itself.
All in all, if you need to keep track of time in any way which is more complex than what the default Windows system clock provides, TimeLeft is a great tool to check out.