If you are a iphone or ipad designer you need to have this cool tool called LiveView.
LiveView is a specialized remote screen viewing application intended as a tool to help designers create graphics for mobile applications, it has also proven to be useful for creating quick and dirty simulations, demos, and experience prototypes.
FOR VISUAL DESIGNERS — Develop pixel–perfect graphics for the iPhone and iPad quickly and easily with a live view of your canvas/artboard while you work. LiveView is compatible with both standard and Retina displays.
FOR INTERACTION DESIGNERS — With your iPhone or iPad tethered via WiFi, you can interact with software prototypes and demos running on your Mac to communicate and iterate your concepts quickly.
FOR EVERYONE — If you’ve ever needed to press a button from afar or wished that you could take a piece of your monitor with you across the room, this app may prove useful from time to time.