Timezone Widget Creator
Four years ago I released a small and simple tool who creates widgets containing multiple clocks displaying multiple timezones.
The widget was static HTML and CSS code generated in PHP on my webserver and called from an object/iframe. It was functional but a bit slow to load those few elements from an external host so I rewrote the application to generate an independent javascript code that you can copy on your website without having to request any external resource. And the best thing is that it will continue to display the right time on your website as it's including the transitions (like when the daylight saving is changing) of the next five years. So now it's fast and lightweight. And I also added some animation on the "matrix" theme!
The best way to use it is generate the widget with the theme "none" and include some styling (like this one) in the CSS of your website, that way it will be the lightest. But if you don't want to do that you can just choose any theme and its style will be embedded to the widget code, you'll just have to copy/paste that to make it work.
If your hosting service doesn't allow you to embed javascript, you can just check the "embed" setting to get a classic object/iframe that will call my webserver.
Oh and by the way it's here to experiment and try it: http://bohwaz.net/misc/tz-widget/
Have fun!