Tight integration with the iTunes desktop application is central to Apple's vision of the iPhone user experience. From its origins as a simple music player, iTunes has grown to handle everything from transferring music, apps and other media to updating the phone's operating system and backing up its contents. However, some feel that this has left the application bloated, and performance issues or simply personal preference leave many users looking for alternatives.
MediaMonkey is a well-established player for Windows, and has a comprehensive feature set for music playback and management. Its free version can transfer audio to and from the iPhone, while the paid Gold version also allows tracks to be converted to lower bit rates during sync, saving space on the device.
Sharepod focuses on providing a simple and lightweight syncing solution, though it can also play music from your iPhone through the computer speakers. It allows media transfer to and from the iPhone, and dragging and dropping of files between itself and Windows Explorer. It is free, though donations are accepted.
CopyTrans Manager can run from the iPhone itself, and can therefore be used on different computers without requiring installation on each one. It allows drag-and-drop addition of media and comprehensive management of files already on the device. CopyTrans Manager does not require iTunes to be present in order to function.