Mike Outmesguine is organizing Post-Tsunami Reconnect: The effort will try to get wireless equipment and expertise to areas of need in the tsunami disaster. Information can be a powerful tool in organizing resources in the midst of chaos. Without a telecom or data infrastructure, the distribution of food, clean water, and medical help could be directed to places that don't need them. Best of luck on this effort.
Direct donations of aid, by the way, are being collected by various groups, including Oxfam and the Red Cross. Amazon.com has devoted its home page to the Red Cross's efforts, and has helped them raise over $1.2 million so far. (The International Committee of the Red Cross's site is down at the moment, apparently overwhelmed by traffic.)
I'm also trying to support Mike's efforts through my blog:
http://dti.ozo.com/index.php?op=ViewArticle&articleId=35&blogId=1
Hope that the Greek wireless communities will offer the best possible.