Chang's said roughly 1 million people clicked, recirculated or otherwise interacted with the Twitter ad.

WSJ: Twitter's Mobile Ads Begin to Click

It's an ad that would otherwise only be seen by voters in a sleepy district in upstate New York.

NPR: YouTube Emerges as Political Tool in Campaigns

Others employ special software to copy the app in its entirety and swap out its automated advertising provider with one of their own choosing, allowing them to generate ad revenue that would otherwise flow to the legitimate app maker.

WSJ: Clone Wars Roil App World