DoubleTwist - iTunes Store replacement [Video]

DoubleTwist is the iTunes-replacement created by DVD Jon for music syncing to a multitude of devices, including the iPhone. It has built in integration for the Amazon MP3 Store. There are 5 million songs currently available.

Unlike iTunes, doubleTwist with Amazon MP3 support is Mac and US-only right now with a PC version coming soon. Sounds like iTunes needs some competition.