IP Address Menu
IP Address Menu allows you to display your current IP address (and other information) in the menu bar and to notify you of changes by email or FTP.
IP in menubar
IP in menubar shows the current IP of your Mac in the menu bar.
LoopBlock is a utility that does hostname and IP address "blocking" by creating loopback entries for the domains specified.
modttl modifies the TTL of packets. Works on OS X and FreeBSD.
Router IP Address
Router IP Address is a small utility for discovering the dynamic IP address assigned by your Internet Service Provider (ISP) when you have a router connecting several computers to a single internet connection (cable modem, DSL, or telephone modem).
SubnectCalc is a tool to help you to make the network IP addressing.
SubnetMapper is an admin's quick tool to map and keep track of managed IP networks, track free ranges that are available for assigning, and document the network setup. It has been designed to help admins manage and document small to medium networks. It prints and displays freely colorable maps of your network.
Whois allows the user to lookup the Regional Internet Regsitry (RIR) information for a given IP Address, also returning the contact information for that IP Address.