A lot of people probably won't have a need for this as they'll have another device to take care of this task already (I know we usually do), but there are a few rare occasions where nothing else is available to update DDNS services with a current IP.
As a little by the by (and this might seem completely senseless to some) but maybe extending the above feature to send a daily email with the current public IP. This would help for devices that have remote management outside of web interfaces.
Keep up the good work!