Angry Birds may just be a 99 cent app, but it's spawned a sequel, inspired a theme park franchise, and is now considering an IPO. Reuters' Tarmo Virki reports that Rovio Entertainment, the maker of the wildly popular game Angry Birds series, is eying a $9 billion IPO bolstered, in part, by the success of Angry Birds Space, which has been downloaded more than 50 million times since its debut in March

You can already tell the makers of this mind-numbingly simple but insanely addictive game are getting a little cocky. In November, they shot down a $2.25 billion acquisition offer from Farmville-maker Zynga and last week, an Angry Birds theme park opened in Finland (believe it or not: the first Angry Birds theme park opened in China last year). According to The Daily News, the Särkänniemi Adventure Park will boast 12 rides including a roller coaster, lighthouse and an "adventure course, along with themed food areas." Still, according to Reuters, the displays of excess are deserved: Since Rovio launched Angry Birds in late 2009, it has achieved more than 800 million downloads and 200 million monthly users by the end of 2011. Here's what that kind of success can buy: