Here’s an AppleScript you can save as a service that will show your router’s IP, your local network node and your external IP, if connected. Save it as a service and you can assign it a nice little hotkey. Pressing the ‘Copy’ button will display a menu that lets you choose which IP address you want to copy to the clipboard. If the connection request returns a timeout, hit the ‘Try Again’ button (or check your connection… 😉 ).
Tip: If you’re not familiar with using AppleScript yet, see my intro getting to grips with AppleScript for a guide to the basics! If AppleScript’s not your thing at all, download my free app FastTasks that will show you all your IP addresses and a whole lot more too!