We could add services that implement the dyndns2 protocol, though (If there are enough requests and the service seems stable). For that, you may PM me with an URL to the API page of the provider.
My vote for all-inkl.com, as well. It is a webhoster that offers ddns for your hosted domains. As far as I know, they use the dyndns protocol, so you would need to allow a dyndns custom entry that points to a different server than members.dyndns.org.