I made a small clock widget to display the current time and "date" as well as where in the day/night cycle the server currently is. I figure there might be interest in this from other server operators and you can check it out (on a static map) at http://sunkid.github.com/minecraft-sundial/
On startup and occasionally afterwards, the widget gets the current number of clicks (the 'Time' value from level.dat) from the server. It calculates the "date" based on converted wall-clock seconds since the epoch, where a wall-clock second is 72 seconds on a minecraft world. Between updates from the server, the time, date, and dial are updated using the browser's clock.
Here is the git repository... get the distribution while it's hot! If you decide to use it, I would appreciate a pointer to your map!
EDIT: I did quite a bit of code clean-up and added a github hosted demo page... check it out!