Remember a few months back when online retailer Overstock.com started promoting a new domain name O.co? It began by touting it as its "new shortcut," but recently launched an advertising push declaring "Overstock.com is now O.co." It even had the name of the Oakland NFL/MLB stadium, the Overstock.com Coliseum, changed to the O.Co Coliseum.

But now, according to a recent article in Advertising Age, Overstock is backing off the O.co push, and returning to Overstock.com in online ads and television ads for the holiday season.

Overstock's president Jonathan Johnson was quick to point out that the retailer is not abandoning the short domain altogether – rather, it is just "stepping back" from it temporarily. Apparently, even though consumers appeared to respond well to the O.co ads, many were confused when it came time to type the domain into their browsers. Instead of O.co, a "good portion" of consumers typed in O.com. Like all one-character .COM domains, O.com is not available for registration. So Overstock has decided it will continue its transition to O.co, just at a slower pace; for now it will use the domain for international and mobile efforts.

When .CO Internet S.A.S decided to open up .CO, the ccTLD for Colombia, to second-level registrations by any person or entity in the world in July 2010, some began claiming that it would be a good alternative to .COM. (Previously, entities had to register domains at the third level, using domains like Domain.com.co or Domain.org.co.) And yet, even with a retail giant actively promoting a .CO domain name, many U.S.-based Internet users still default to .COM.

According to Opportunity.co, more than one million .CO domain names have been registered, but that still pales in comparison to the nearly 100 million registered .COM domain names. In fact, many established companies registered their brand names in .CO as more of a defensive move to prevent cybersquatting. While some newer ventures opted to go with .CO (perhaps because the .COM version of their name was taken), it's clear from the O.co case that the ccTLD hasn't really caught on to the extent that some believed it would.

The debate over .CO – whether it can be a viable alternative to .COM or if it is just a gimmick – continues. For example, Overstock.com, the popular online retailer, recently introduced the new O.co domain name, but is billing it as a “shortcut” to the Overstock site rather than a standalone brand.

While reading the TechCrunch blog, I recently came across another example of a company using .CO for an interesting purpose. Go2 Media is a service that connects mobile publishers, local audiences and advertisers through content and location-based advertising. It owns the domain Go2.com and uses it to host its consumer-oriented site. However, the company does not own Go2Media.com – this domain is registered to a Korean man and has no content other than a link to DomainCA, a Korean domain registrar.

Instead, Go2 Media owns and leverages Go2Media.co for its business-oriented site, where it hosts information for publishers and advertisers. What likely happened was, the company saw that Go2Media.com was already registered, and sought a solution. But instead of attempting to reclaim the domain Go2Media.com through UDRP (a search on UDRPsearch turned up no filings over that domain) or other means, the company chose to register Go2Media.co as an alternative. When push comes to shove, though, Internet users in the U.S. are conditioned to affix .COM at the end of Internet addresses, and as such, Go2Media.com receives traffic – undoubtedly visitors seeking the company, not some Korean squatter’s site. At the end of the day, .CO is not a substitute for .COM.