If you have the Apple iPhone 3G with you and want to customize the look of wallpaper, dock style and change the theme, then this online application called iPhone Theme maker is the one to help you create a customized themes for iPhone. And the best part, this is free to use.
Just visit iPhone theme maker website and you will have option to generate your iPhone theme wallpaper,choose dock theme style and status bar or add icon to customize the theme look.
After creating the theme you will get a URL of the theme, now open the installer.app from your apple iPhone, you will get a welcome message on the screen.Click on sources and then edit. Now click on Add and type: http://iphonethememaker.com/<YOUR SOURCE URL> and then hit OK.
Click done and refresh the menu to see theme which is added in the Sources under ‘Themes’.