Just a couple of days ago, I had a "well, duh" moment that I hadn't really thought through, regarding the use of URL shorteners and their domains.
A URL shortener is a site where you can take a long URL that's not very easy to remember - such as http://www.theresagreatsiteyouhavetosee.com/and-the-page-is/in-a-directory/andheresthepage.html - and shorten it to something more manageble, like http://sho.rt/url. The URL shortening service simply redirects visitors to your original link, and many services also include tracking and statistics tools.
One of the most popular is http://bit.ly, mainly because it is easily integrated with Twitter. You can shorten a URL and send it out via Twitter all at once. Another service is http://ow.ly. Both feature extremely short URLs, and create their short URLs using 4-6 alphanumeric characters.
What I was aware of with these sites - but didn't really think about - was the top-level domain. Top-level domains ("TLD") are the part after the last dot in the overall domain, and tell you what type of site you are visiting. The most well-known TLD's are .com, .org, and .net, which are intended to indicate a commercial, organizational, and network site respectively. In addition, there is .edu (indicating an educational site, reserved exclusively for higher institutions), .gov (governmental sites), and .mil (military establishment sites) - all three of these are closely governed. (Whereas any user can register a .com, .org, or .net domain, such is not the case with those three; they are internally distributed.)
The three-character domains are certainly not the only ones - some newer TLD's with four or more characters like .mobi, .info, and .name have come into use in the last few years. The other TLD set that have been around since the beginning are county codes. For example, sites that end in .us are United States organizations. (Sometimes these are subdivided further, for example many school systems use .k12.XX.us, where XX is their state abbreviation.) Other country codes are .uk for Great Britian, .ru for Russia, .ca for Canada, .au for Australia, and so forth. (Wikipedia has an article listing almost all of the top-level domains, country-based or otherwise.
The whole point of this post is this notion of country code TLD's - particularly, using them for something that's not country-specific. Some country codes have become desirable of late because of their potential use in creating easily-remembered URLs. For example, Columbia's .co is a possible alternative to .com, as both could stand for company. Another well-known domain (but not necessarily the country) is .tv, which belongs to the country of the islands of Tuvalu. (Do you know where they are? I had to look them up.)
In the case of my previously-used URL shorteners, they use the TLD of .ly, which is Libya. With many more services trying to capitalize on the adverb-conjuring .ly domain, Libya has now begun to crack down on registrations and activities of those sites - it has disabled some services which it claims is in violation of religious law.
Another URL shortener service that I was recently introduced to is http://goo.gl - Google's service. The one thing I don't like about it (as compared to my previously-used bit.ly) is that you can't create customized shortened URLs - you must use the 5-character string Google creates for your link.
But as its domain is based in the much more stable Greenland, it might still be a wise switch.