An Axis camera can automatically do update requests to dy.fi and keep a dy.fi name pointing to itself. This has been (so far) tested with an Axis 2100 Network Camera.

1. Reserve a dy.fi name for your camera (for example, webcam.yourname.dy.fi).
2. Configure a dy.fi name as the hostname of the camera (include the dy.fi domain in the hostname), as seen on this screenshot of the TCP/IP configuration page.
3. Configure HTTP Notification of IP address changes, with http://www.dy.fi/nic/update as the URL, no custom parameters, no proxy, and your dy.fi login (email address & password), as seen on this screenshot of the Notification configuration page.

Thanks go to lakki for the testing and screenshots!