The iOS platform isn't the only way to make money on the mobile apps scene.

Tech news site Electricpig took a look at eight groups that have made it big – more than six-digits big – with hit Android apps.

Better Android Apps, for example, has made approximately $1.34 million from purchases of its hits Better Keyboard and Open Home. Yongzh created emulators for the PlayStation, Sega, Nintendo and Atari systems, and gathered about $1.81 million from sales of these apps.

“Conventional wisdom told us that to be successful, we had to focus on iOS. Conventional wisdom was wrong," said Gary Gattis, CEO of Spacetime Studios.

That certainly seems to be true with the tower-defense game Robo Defense. It has also been a big winner, netting creator Lupis Labs more than $2.09 million.

An estimated 3.7 billion Android apps have been downloaded to date, according to AndroLib. Many developers wish that number would rise at a faster rate and are counting on tools like in-app payments to spur app purchases and developer earnings. However, that hasn't stopped developers such as Eddie Kim, creator of Car Locator, or almost anyone else on this list, from netting big profits.

These high sales figures illustrate that Android's app market is finally coming to fruition as a solid distribution platform, where software programmers can make good money. Within months of the opening of Apple's App Store in the summer of 2008, a few lucky programmers quickly struck gold with hot sales of their apps.

Android has been around for about the same time, and only now are we beginning to see comparably high sales figures for Android app makers. Though Google's app market has been slower to mature, these success stories should give programmers more incentive to make killer apps for Android-powered tablets and smartphones.

Beautiful Widgets netted its maker, LevelUp Studio, more than $934,000. Halfbrick Studios (maker of Fruit Ninja) has netted more than $242,000 after porting its iOS favorite to Android.

Other big winners, thanks to pop-up advertising, include Rovio, for (what else?) Angry Birds, and Arron La for Advanced Task Manager.

Spacetime Studios' Pocket Legends, a 3-D MMO, has managed to garner profits of $8,000 per day from in-app payments, making it a shoo-in for six-figure earnings in the not-too-distant future.

“The Android platform has seen phenomenal growth, and it’s great that new avenues for app distribution are opening up,” Rovio CEO Mikael Hed said in a recent news release.

The addition of new marketplaces like Amazon's App Store is proof, showing that Google's OS has the potential to be just as lucrative as Apple's, and companies want to get in on the action.

Spacetime's Gattis summed up the Android app scene pretty nicely: "In some ways, it's kind of like the wild, wild West," he said, "but that's where the Gold Rush people made their claim."

Image: Bad Piggy Bank (Rovio)

Meet The Android App Millionaires [Electricpig via Android Guys]