we would like to see "domain aliases" - not parked domains! Domain alias where the one domain is a real alias to some other main domain. DNS are changed for both if updated, emails work for both on the accounts that are created on the mail domain, www ofcause also.
often you would by conviator.com conviator.net conviator.dk and so on. One is the main and then the rest should aliases and make sure not only www is working (as with parked domains) but also that emails on all domains and DNS changes are working for all domains.
we are not to happy to have to sell them one webhotel per domain and a webhotel where you can have more domains are not limited in use to one actual website.