Domain hack is a pleasure, even domain hack could be a lucrative business for the domainer, because sometimes the prices can be much higher, i.e. compared about.me with aboutme.com prices.

Domain hack could mean combining the type of top level domain to pronounce certain words or keywords, e.g. inter.net, who.is. And the most popular domain type to use is the ccTLDs, like .me, .it because it is very short and widely used in a dictionary words so it's easy to find the right words or keywords.

For the domain hack, I prefer to use the ccTLDs already considered as gTLDs by Google so it can be used haphazardly, not limited by a particular country. Domain .la is for Laos, but popular in some countries due .la could be interpreted as Los Angeles or Latin America.

With more and more websites are created, then the Generic top-level domains (gTLDs) such as .com, .net, or .org that are nice, short and in accordance with your business becomes much less.

Of course we can switch to using Country Code Top Level Domains (ccTLDs) such as .jp, .de, .ca or any others ccTLDs that corresponding to your country, but it would be a problem if you do not target your site for a specific geographic.

The solution is to select the ccTLDs that are treats as gTLDs:

.ad
.as
.bz
.cc
.cd
.co
.dj
.fm
.gg
.la
.me
.ms
.nu
.sc
.sr
.tv
.tk
.ws

Regional top-level domains (rTLDs) such as .eu, .asia will always treated as gTLDs. For more details you can read the Webmaster Tools Help related to Geotargetable domains here.

Note: Above list updated on July-22-2011 by Google, and the list may change over time.