BeatScratch

One part keyboard with 128 effects, one part drum machine, one part music viewer/player, one part desktop-class sequencer, BeatScratch is all you need. It's your one-stop:
* Metronome, with tempo switching between Sections and the option to customize the Drum Part
* Musical Notepad: Make sure you can play your idea. Tap in at whatever tempo is comfortable, and play it on the on-screen keyboard. Hit the "x1" button to play it back at your desired tempo!
* Sequencer and composition tool: Layer recorded Melodies atop each other in Sections using BeatScratch's forward-thinking UI.
* General MIDI Synthesizer: Any keyboard plugged in to your phone - or connected over Bluetooth - can be used to play the 128 built-in effects. Melodies can be recorded the exact same way as with the on-screen keyboard, and pitch wheels/damper pedals can tap you in.
* MIDI File Builder: BeatScratch Scores can be exported to MIDI files with a variety of options.