SimpleMidiPad

SimpleMidiPad turns your iPad in to a MIDI CC controller data source, with four X/Y pads sending three CCs each. SimpleMidiPad can use wireless MIDI via the Apple MIDI Network Session, or on Windows via the rtpMIDI driver, or via a hardware interface using the Apple Camera Connection Kit. It can also use all popular CoreMidi-compatible MIDI interfaces designed for the iPad.

DroneStation

DroneStation is a simple "analog-style" 2-oscillator synthesizer with an unique and easy-to-play control system.
DroneStation is designed to allow easy synthesizer playing for the non-musician, yet enable subtle expression for the musician that isn't available with most synths available on hand-held platforms.