Ovid,

If speed is an issue, why not fork off some children, and search for all variations at once? Assume you the minimal is a domain.TLD, so www.cs.flinder.edu.au would give you:

www.cs.flinder.edu.au
cs.flinder.edu.au
flinder.edu.au
edu.au
[download]

You can further optimize this by taking a listing of non-foreign TLDs (.com, .net, .edu, .mil, .org, etc) and only running this if your domain does not end in one of these.

Not a real solution, but perhaps a workaround.

=Blue
...you might be eaten by a grue...