Dec 4, 2010 14:00 GMT  ·  By

For mobile app developers, the most reliable way to make a living has been, well, selling them. There are plenty experimenting with in-app advertising, but there haven't been any run-away successes so far. But one of the most popular apps of all time, Angry Birds, is actually seeing quite a lot of success from its ad-supported version versus the paid app.

Angry Birds has been a massive hit and has been downloaded more than 30 million times across all the platforms it's available on. 12 million of those have paid for the app so it's clearly a popular game.

On Android devices though, the game's maker, Rovio, went with an ad-supported model rather than selling the game like on the iPhone. Part of the reason may be that the Android Marketplace's payment platform isn't great and it's not available in too many countries, but that is besides the point.

The Android version of the game has been downloaded 5 million times and Rovio is on track to generate $1 million in revenue per month by the end of the year, according Rovio's Peter Vesterbacka.

This is less than what the company would have made if it sold the game, but this is just for one month. The more time people spend with the game, the more money Rovio is going to make. In a few months, the 5 million downloads could prove more valuable than 5 million sales.

It's easy to see why Google would want to tout this, so they're highlighting the fact in a couple of blog posts along with a video of Vesterbacka.

"We invited Peter Vesterbacka, 'The Mighty Eagle of Rovio,' to share insights into the creation of this mobile game and advice for developers on how to think about building a mobile business," he said.