OnLine Tools
dnsreport.com
dnsstuff.com
grc.com
Open Port Tests
ordb.org/submit
Open Relay Test
directupdate
Great little tool for Updating Dynamic IP Info
www.2wire.com www.dslreports.com
speed tests
http://www.infosyssec.com/infosyssec/ipsectools.htm
whois, nslookup, nmap from their site
www.samspade.org
spam tracing tools