Dead-simple in-app notifications. Notifications slide up from the bottom of whatever view they're attached to and slide back down when you or the user are done with them. Great for indicating that something is happening (a feed is being refreshed, for example) or that something has just happened (there was an error sending something, for example) without throwing up a UIAlertView. You can customise the notification text, the notification level (which affects the background color of the notification — red for error, blue for message, and green for success), the target/selector that's fired when the user taps the notification, and whether or not the notification has a spinner.