SparkInspector.com , go check it out. I would rate it in the top 5 developer tools for iOS devs.
Spark helps you debug your app UI at runtime, by visualizing the app view hierarchy. Including the views in the viewport as well as the other views that are outside of the viewport or just hidden.
I previously posted about a similar Firefox Development tool that 3D visualizes the divs and css layout of a webpage (a fantastic tool for debugging the UI of a website).
This helps you visualize any user interface layout issue that your app has. This is powerful because when you have several views on top of each other these issues may not be readily apparent.
Since Spark Inspector runs in realtime, as you move around your app it can also help you understand what views and components you are holding in memory at any point in the app.
Last but not least Spark even lets you choose between using your simulator or a live device. You can connect an iphone over bonjour wifi. Wow, even nailing the bonus points.