Sort by domain name?

[js]

Hi list,

I have a list of URL and I want to sort that list by the domain name.

Here, domain name doesn't contain subdomain,
or should I say, domain's part of 'www', mail, news and en should be excluded.

For example, if the list was the following
------------------------------------------------------------
http://mail.google.com
http://reader.google.com
http://mail.yahoo.co.uk
http://google.com
http://mail.yahoo.com
------------------------------------------------------------

the sort's output would be
------------------------------------------------------------
http://google.com
http://mail.google.com
http://reader.google.com
http://mail.yahoo.co.uk
http://mail.yahoo.com
------------------------------------------------------------

As you can see above, I don't want to


Thanks in advance.