When companies the size of Google decide to buy domain names and specifically, domain names the size of g.co, they shell out a lot of money. When Google bought this domain recently, they're said to have paid to the tune of $1.5 million for it. Google would most likely use the domain to host its array of apps, everything from Gmail to Google Docs. The .co line of domains belongs to Columbia. A whole bunch of companies own sites on the .co domains including Twitter (t.co) and Amazon (a.co).
A compact domain, merely a luxury
The CO Internet company is run with support of the Columbian government. As of now, g.co isn’t accessible for any services. Instead, you’re just pointed out to Google’s official URL shortening service – goo.gl. The .co domain range is close to a year old and has some 1 million domains registered as of early June. Not all of these domains are obviously single alphabet ones. Shorter domains are a bit of a novelty. It makes accessing sites a little simpler and quicker. It’s only sensible for dot com moguls the size of Google who can afford to buy such exotic domains considering the user base they have.