miniSynth Pro for iPad
miniSynth Pro is a virtual analog synthesizer with some great features and cool sounds. It has FM and Subtractive synthesis as well as monophonic and polyphonic capabilities. The newest update is version 1.6 and has some great additions like virtual MIDI support, which allows you to use the app’s interface as a MIDI keyboard in conjunction with other programs. It has re-sizable keyboards, audio copy and paste, and the ability to create and save presets.