A windows System Tray Icon develop on Qt, for renew your external IP in "freedns.afraid.org"
You need to create a free account on http://freedns.afraid.org
On the application you can select the period of time for update your external Ip, in case that is already update with the last IP it's will not show the update, only show update when your IP was change for your Internet provider.
/Roberto Alonso Gómez