For anyone willing to take the risk, another 3rd party service currently free was promoted on HN 6 months ago:
https://news.ycombinator.com/item?id=14856277#14858784
>opie34: A friend and I put together a free dynamic DNS service [1] offering cool custom domains aimed at the Raspberry Pi community (and similar hardware hackers.) It's not strictly a hardware project, but it's a crucial building block for any network-enabled Raspberry Pi project, and we'd love your feedback.