Freetune Advance is a”Tonal Guitar Tuner”. Here is what the author says:

I have written my first GBA program and it is Tonal Guitar Tuner, you play the note and tune your string along with the tone.You do have to have a firly good ear to tune along to a tone but even if you haven’t yet developed a ‘good ear’ it will still help you get the strings very close, then you can tune across the strings as you would normally do.Thanks to OrR for his GBAkkord which inspired me to write FreeTune Adv.

http://www.gbadev.org/