http://adage.com/article/news/o-overstock-backs-o-change/230...
Overstock.com changed their primary domain to "o.co" in what I can only assume was an attempt to make people type less.
Customers rarely entered "o.co", instead they entered "o.com" because that's what they expected to domain to be.
Result: tons of cash wasted as Overstock reverted to "Overstock.com".
Get a .com and move on.