IP Broacaster displays your local (LAN) and internet (WAN) IP numbers in the menubar
IP Broadcaster
IP Broacaster displays your local (LAN) and internet (WAN) IP numbers in the menubar. Includes options to toggle wan and lan display, and to sing the currently displayed number in any of Apple’s luscious voice. IP Broadcaster is universal binary.
http://10base-t.com/macintosh-software/ip-broadcaster/