Net-Tools
http://users.pandora.be/ahmadi/nettools.htm
On the go Tools
http://www.all-nettools.com/toolbox
http://www.dnsstauff.com
I have found the Net-tools 5 to be very useful as it contains everything i need in a hurry including Nmap between the two online toolboxes i have found dnsstuff more reliable than all nettools.
enjoy.