.to

.to is the Internet country code top-level domain (ccTLD) of the island kingdom of Tonga.
The government of Tonga sells domains in its ccTLD to any interested party. The .to ccTLD is administered by the Tonga Network Information Center (Tonic).
Because to is a common English preposition, it became popular to craft memorable URLs called domain hacks that take advantage of this; URL shortening/redirection services (e.g. go.to) are a popular use. Other domain hacks do not use the to as a preposition, including Daniel J. Bernstein's website cr.yp.to, London web development company Potato p.ota.to, and uploading services like uloz.to (which means "save it" in Czech and Slovak).
"T.O." is also a common nickname for Toronto, Ontario, Canada and is used as a city domain extension as exemplified by popular Toronto sites www.dine.to and www.jobs.to . This domain extension is also used for the city of Torino (Turin), Italy.
As the .to domains are...