1. There is this story about a Hungarian startup that went from broke bootstrapped mode to covering all costs + salaries in one day by changing the icon of their free book iPhone app.

They were able to differentiate themselves in a crowded market, with lots of similar products, with a small change to their icon that had nothing to do with the actual product itself.

2. Here's another story. I know of another app by a Mexican developer, with hundreds of thousands of fans, with a fraction actually using the app (usually it's the other way around, as only a fraction of your users care enough to become fans). The app was able to gather such a number of fans solely because of its name El Ahorcado which means Hangman in Spanish. People became fans of the app because it reminded them of the game which they played as children.

3. Here's another example: @BreakingNews. Michael Van Poppel, whom I consider the European equivalent of Matt Drudge, started a twitter account with the catchy BreakingNews username, and as a result acquired hundreds of thousands of followers before selling the account to MSNBC. His strong reporting skills in addition to a catchy username were both strong influences in acquiring a large follower base.

So next time you're building an app or establishing a brand, think carefully of the name and icon you pick for your idea. 

Traditionally, brands have had dozens of touchpoints to showcase their identity. But in our current world of feeds, app leaderboards, 140 characters, and url shorteners, your username + icon combination will account for a much larger share of your brand exposure and have a disproportionate influence on customer acquisition. Choose them carefully.