Recently a new and particular nasty worm has been discovered, called "Loveletter". It distributes via the Outlook email program with a topic named "ILOVEYOU". It steals passwords, destroys system files containing several key extensions as well those with extension "jpg" and "mp3". Meanwhile a variant has surfaced that distributes itself under the topic "Susitikim shi vakara kavos puodukui". If you get an email with either one of those topics, delete / trash immediately.
More information on this worm and how to clean this one up can be found at F-Secure (and presumably at every major virus scanner's site by now). This might also be a good time to remind people to never ever execute email attachments.