bs-16i is a 16 multi-timbral playback sampler. It supports SoundFont / DLS and can be used for keyboard instrument, MIDI sound module, and MIDI player.

(App Store / GooglePlay)

swipestrings is a musical instrument application with an interface similar to the fingerboard of a fretless guitar. Leveraging the fantastic multi-touch screen of the renowned iPhone and iPad, it allows you to express subtle pitch variations in real time, closely resembling the fretless guitar interface. With practice (of course, as everyone would need), this app enables you to create rich musical expressions comparable to playing a real instrument.

(App Store)

m16 is a MIDI player application that supports SMF (Standard MIDI File) for GM (General MIDI) specification.

(App Store)

bs-spectrum is a Simple FFT spectrum analyzer application.

(App Store / Google Play [Paid version / Free version])