Investigating IP's

http://centralops.net/co/
http://www.all-nettools.com/toolbox
http://www.completewhois.com/
http://www.samspade.org/
http://www.dnsstuff.com/
http://www.demon.net/external/

Domain name investigation:

Whois.sc is now:

www.domaintools.com
http://whois.domaintools.com/
http://whois.webhosting.info/

RWHOIS:

http://www.rwhois.net/rwhois/prwhois.html

Spam database / cross reference lookup :

http://openrbl.org/
http://ipindex.homelinux.net/index.p...check_on_dnsbl

IP/AS/ASN search:

http://www.fixedorbit.com/search.htm

AS trace:

http://www.fixedorbit.com/trace.htm

The general RIR lookups :

http://ws.arin.net/cgi-bin/whois.pl
http://www.ripe.net/whois
http://www.ripe.net/db/whois-free.html
http://www.apnic.net/apnic-bin/whois.pl
http://whois.samoanic.ws/whois.dhtml

Traceroute site listings:

http://www.traceroute.org/
http://www.geektools.com/traceroute.php

IP Index sites:

http://ipindex.homelinux.net/
http://www.flumps.org/ip/index.html

Site Host monitoring:

http://searchdns.netcraft.com/?host
http://uptime.netcraft.com/up/graph
http://www.hostcount.com/

IP/netstat monitor:

http://www.sysinternals.com/Utilities/TcpView.html

Freeware Packet Sniffers to help identify the source of any suspect packets/connections leaving your computer:

Smartsniff [ no install required ] :

http://www.nirsoft.net/utils/smsniff.html

What is transferring:

http://www.wfshome.com/wit.htm

Packetmon:

http://www.analogx.com/contents/down...twork/pmon.htm