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.