Starting now, if you would like to maintain your free Dyn account, you must log into your account once a month. Failure to do so will result in expiration and loss of your hostname. This activity helps us eliminate hostnames that are no longer needed and/or dormant. Note that using an update client will no longer suffice for this monthly login.
For anyone reading this and wondering how to accomplish what BarryG's doing, the trick is to use a CNAME like myhost.mydomain.com -> myhostmydomain.dyndns.org.