Dyn stops its free service.
I've chosen Spdns as an alternative. A service of Secure Point GmbH .
One may invest up to 5 hosts there and can choose between several top-levels-domains.
Registration is simple and straightforward and requires only a username/password and an email-address for submission.
You can reach the service at spdns.de .
The only problem was that my router has no way to deal with this service.