ZYNGA!
They're a social networking company whose business practices are completely immoral and outrageous, yet they just about toe the legal line to avoid copyright infringement.
For their craptastic business pratices go to this, http://en.wikipedia.org/wiki/Zynga and scroll down to "controversies."
Basically they have made billions (company now worth $15-20 billion) by taking other peoples social games, (easy to understand but unneccessarily super grindy) ripping off the game mechanics and looks, and changing just enough to avoid plaigerism. Then they fill the game to the brim with microtransactions, spam the social networks with as many adverts as possible for their games and file bogus lawsuits against the original companies games, which are almost invariably independant indie developers, and can't afford to fight the lawsuit, forcing them out of business.
From wikipedia: "The launch of Mafia Wars sparked a lawsuit from the makers of Mob Wars. An attorney for Psycho Monkey, the creators of Mob Wars, said that in making Mafia Wars, Zynga "copied virtually every important aspect of the game." The suit was settled out of court for $7?9 million.
Ars Technica noted that Zynga's Cafe World and Playfish's Restaurant City were "nearly identical"; Cafe World was released six months after Restaurant City. Its gameplay, design, graphics, avatars, and even in-game items are almost identical to the ones in Restaurant City. Many players who have played Restaurant City and Cafe World have noticed the extreme similarities between both games. In addition, journalists have remarked that Zynga's FarmVille is similar to Farm Town, with Peter Jamison calling it "uncannily similar.""
I actually played Farmtown for a while with friends, and it took me about a month to realise that all the spam for Farmville was in fact a different game, they were that similar.