Airy Synth is a free Audio Unit Synth. It's a very basic single oscillator synth with a vowel filter. Source code is included.
They also have AUStk (A demo of integration of Stk instruments into an AudioUnit) and Voweler (A simple vowel filter, with the possibility of mixing two vowels) available for free download.
They also have AUStk (A demo of integration of Stk instruments into an AudioUnit) and Voweler (A simple vowel filter, with the possibility of mixing two vowels) available for free download.