Are you having issues with any of the iOS stores? Such as App Store, iBooks or iTunes?

For example, I occasionally see an app that indicates that it has an update available in the app store, but the Update button doesn't show—just the Open button.

Clearing the store's cache fixes this.

In order to clear the store's cache, simply tap one of the buttons at the bottom of the store ten times in rapid succession. For example, in the App Store app, you can tap one of the following: Featured; Top Charts; Explore; Search; or Update.

The screen will momentarily go blank, and the cache will be cleared.

Thanks to Zachary Drayer for this little-known tip!