Add this piece of code:

<script type="text/javascript" src="http://www.communia.info/MayDay/pool/count-mayday.js"></script>

wherever you want, and you'll get a countdown to Mayday like this example

This javascript is working great with most sites. despite this maybe you get better results with:

<script type="text/javascript" src="http://www.communia.info/MayDay/pool/count-mayday-table.js"></script>

If then you won't get good results follow look at troubleshooting, or hack the code ;)

Troubleshooting:
if you have problems with the vertical-align of the number:
You must include this code where you want to place the widget, in this code you have to find "top:-50" and adjust this number...IE not tested...

 
<script  type="text/javascript">

var countdown_time=Date.UTC(2008,4,1,-1);
var now=new Date();
var now_millisecs=now.valueOf();
day_cnt= Math.ceil(( countdown_time - now_millisecs)/86400000 );

document.write('<style type="text/css">#countdown-cont{width:"217px";height:"140px";} #countdown {position:relative;width:125px;right:40px;top:-50px;text-align:right;font-size:48px;font-weight:bold;color:#f00;height:12px;font:Arial,Helvetica, sans-serif;}</style><div id="countdown-cont"><a href="http://www.euromayday.org"><IMG src="http://www.communia.info/MayDay/pool/countdown.jpg" width="217" height="140" align="left" border="0"></a><div id="countdown">'+day_cnt+'</div></div>');

</script>