PixelWave is an experimental synth with old school pixel interface.
• multitouch arpeggiator;
• it is possible to draw waveform and play it at the same time;
• export to WAV (via iTunes File Sharing);
• copy to pasteboard;
• nine predefined waveforms;
• changeable number of octaves (from 2 to 6);
• Low-Pass filter (smoothing);
• MIDI IN support;
• Audiobus and IAA support.
Also if you want to draw the spectrum of sound, check my other app - SpectrumGen.