Clustering is a musical practice tool for iOS. It lets you setup a cluster (or any chordal structure) and use it for practice material. By taking the cluster through a series of root movements, you can bring some fun and interesting discoveries into your practicing. I've always found clusters to be very inspiring and challenging. Take an inspiring chord/sound through the cycle of fourths, or chromatically or just repeat it. It's such a great way to enhance your practicing.