I was just preparing a list of online websites which are very good for performing
reconnaisance, here it is

http://www.google.com
http://www.samspade.org
http://msv.dk
http://www.pwhois.org
http://www.networksolutions.com
http://www.sec.gov
http://www.arin.com
http://www.samspade.org
http://www.netcraft.com
http://www.allwhois.com
http://www.betterwhois.com
http://www.network-tools.com
http://www.geektools.com

I list google first as nothing beats it.