I saw a television commercial for Overstock.com the other day. I was immediately struck by the similarity of their logo to that of Opera Software. I've been familiar with the Opera “O” for a long time, but Overstock's version is new to me. The image below shows a comparison of some of their logo treatments.
I think I'd be a little annoyed if I was Opera. Their logo design has been around for ages, and it is not inconceivable that the two companies might find themselves in similar commercial territory in the near future. Of course, Opera's “O” looks way cooler than Overstock's, so perhaps it doesn't matter.