Well you have to wonder how the client would display the actual clock face:
the only way I can think of is a program that can create gifs/jpegs on the fly - but then it wouldn't update withouth further server interactions, would it? If you did want it to update the clock-face in real time, then the client would be constantly loading a new picture.... (or at a minimum every minute (i.e. no second hand) ... and this would be bad for the server and doubly bad for the client (you would cripple a 56K connection unless you were careful with quality and sizes).
I did see this, though:
http://g04.com/html/modules.php?name=News&file=article&sid=51 and I thought that that was quite elegant.