The countdown event module allows you to select a date and time and it will
render a countdown in a block, showing days, hours, minutes and seconds
to the event.

Various options can be configured in the 'block configure' menu option.

You can add your own label to the countdown ie 'countdown to my birthday',
or 'countdown to new year'.

Also you can select your colors (in hex or html name) for the label text,
countdown numbers and the background colour for the countdown numbers.

The module is written in simple javascript and so it should be compatible
with a wide range of browsers.
