IQuium Pty Ltd has StringMaster (iTunes Link) for the iPad in the iTunes App Store for FREE (regularly $3.99) for a limited time.

StringMaster is an advanced iPad application suitable for beginner through to intermediate Guitarists and other fretted instrument Musicians. With its beautiful, natural sound, StringMaster supports a wide range of instruments. The chord building and detection, comparison between instruments, fretboard learning system, scales and advanced song writing tools are all supported with any instrument in any orientation, and with tremendously flexible alternate tuning and capo support.

With its high resolution graphics, StringMaster has been fully optimized for the iPad Retina Display, and also works with the iPad 1 and 2. Note StringMaster is an iPad Only application and is not supported on the iPhone.