Playfish is a company established in Royal Borough of Kensington and Chelsea, London, England in 2007. This is the company famous for creating Casual Social Games for Facebook and other social media sites.
One of their best successes is the creation of an artillery, turn-based social game called Crazy Planets. Utilizing some games like Crazy Planets with a monetary system known as "Playfish Cash", their business model functions based upon Micropayments. The majority of virtual products of Crazy Planets can be acquired by spending Playfish Cash.
This company was bought by Electronic Arts in November 9, 2009. It was announced that their acquisition to pay for Playfish is USD $275 Million. Here's a press release for more information. For more information about their company, see the official playfish site.
Their newest game as of February 2010 is Gangster City, a flashy graphical crime-oriented game similar to Mafia Wars.