Turns out our passing thoughts are worth a lot. Twitter has become one of the hottest companies in Silicon Valley—with some market estimates placing the social-media site’s value at $8 billion to $10 billion. The valuation comes as a shock to some, because Twitter’s 2010 revenue was only $45 million, and it's estimated to have revenue of between $100 million and $110 million in 2011. Both Google and Facebook have had low-level talks with Twitter about buying the site, although they’ve reportedly gone nowhere. Twitter executives’ motives remain unknown, but the company has been experimenting with ads, and it buffed up its workforce last year.