The Smurf Amplifier Registry (SAR) lets you probe Internet connected IP networks to see whether or not they are configured in a way that will allow perpetrators to use them for smurf amplification. http://www.powertech.no/smurf/
A simple, effective, and straightforward method for network administrators to prohibit DoS attacks which use forged IP addresses. http://www.faqs.org/rfcs/rfc2267.html
Analysis and investigation of the denial of service threat posed by Windows XP, and reports and logs from when GRC.com was the victim of a DDoS attack. http://grc.com/dos/intro.htm