A Domain Hack is when the top level domain (ux.stackexchange.com) and sometimes the subdomain (ux.stackexchange.com) is used to spell out a word instead of being used as a country code (.us, .uk) or organization type indicator (.com, .gov). This results in site names like "del.icio.us".
The resulting names are cute, but are they usable? I can't imagine telling my mother "Okay, just navigate to 'd-e-l-dot-i-c-i-o-dot-us'...". Comunicating such URLs in spoken conversation is awkward at best. If your only interaction with the URL is inside a browser it's largely irrelevant, but still the name might not look like a URL without the familiar .com/etc. top level domain.
Is there data or any good articles covering this issue?