ReSlice - Slice your audio with an advanced, rhythmic arpeggiator and FX.
VOXISO - Online AI-powered vocal and music remover
cassini - Polyphonic Synthesizer for iPhone/iPod touch
Groovebox: Beat & Synth Studio - Make Music & Play Instruments
nlog Synth - Professional Virtual Analogue Synthesizer ::: check nlogmusic at YouTube :::
Scratch Track - Scratch Track is a simple and powerful application that offers services as a recording app to capture song ideas.