Make your app icons boring
Which one of these cars would you notice driving down the street first?
The pink one, right? Now, tell me, which car would you rather drive everyday? The black one? Thought so.
Fast and Furious App Icons
The App Store is becoming a very cluttered place, and in order to stand out amongst the crowd, a whole new art of app icon design has popped up. I understand the attraction. When millions of people might be scrolling past your app, you want something that will shout at them louder than all the others.
Once your app is downloaded though, the shouting is gone. Your app has been picked, and it now sits comfortable alongside the other "chosen ones." But your icon is still screaming at users, and there's no way to stop it.
You've chosen to stand out to your potential users at the cost of constantly screaming at your real users, who are the ones you should be most concerned about.
Dribbble is without a doubt the best place to find Fast and Furious icons. The amount of effort that goes into the work on Dribbble is astounding, and I respect the creators for their art. But just as I'm not going to be stoked to park a lime green Toyota out in my driveway, I'm not going to be excited to put your intricately detailed, color-burst icon on my iPhone.
The best icon in the App Store
If we agree that visually screaming at your users through your icon might be a suboptimal strategy, then what makes an acceptable app icon? Well, it's easy to demonstrate through an example.
I present to you the best icon in the App Store:

This icon does everything the icons that dominate Dribbble don't. It's calm, simple, and understated. It doesn't try to be overly clever, like trying to fit a photorealistic mailbox into a 57x57 rounded square. It uses a simple symbol to reflect its purpose, and places it over a bright, glossy background.
If your app is a utility, make it look like one
Sparrow for iOS has a huge challenge: they're trying to displace Mail, which is one of the core Apple iPhone apps. Their competition comes pre-installed!
Sparrow knows that its users will open the app every single day, just like Phone and Messages. Sparrow wants to be your email utility, and so it smartly designed itself as such.
Let me illustrate through a slightly zoomed out picture.
The Sparrow icon feels right at home next to the other utilities, even more so than Mail itself. The understated, visual appeal of the icon (not to mention the amazing product itself) made the switch from Mail even easier.
Bravo, Sparrow.
I'll go first
The reason I first started thinking about this is that I'm in the midst of a re-design for my movie showtimes app, Cinematic. I decided to take a fresh look at my icon, and came up with something that reflects the purpose of the app. Like Sparrow, I hope that Cinematic will become a utility for my users, who will open it on a regular basis. I redesigned the icon with this in mind, and I'm happy with the way it turned out.
I present the old icon (on the left), and the new icon (on the right).
Let me know what you think of the new icon on Hacker News