Some ideas:
1. I love the Guitar Note Reading drill, however it would prove beneficial to have in the settings section an option to choose the starting fret. In other words, right now on can only quiz themselves up to the fifth fret. How about broadening the drill to include quizzing up to the 12th fret.
2. It would be awesome to have interval drills for the guitar.
For example: the drill displays the X interval and asks for the Y interval above or below which shares the same root as the X interval. The image of the guitar displays the X interval and it is the job of the user to click on the Y interval on the guitar image.
3. A further degree to the interval drill for the guitar could include creating chords when provided with one of the interval locations in the chord.
For example: The user is provided with the location of the 5th of a dom7 chord. It is the job of the user to click the spots on the image of the guitar fretboard for the root, 3rd, and b7.
In this drill the chord being quizzed can be random and can be controlled and isolated within the setting menu. The number of intervals of the chord, in the example above the interval provided being the 5th, can also change. So perhaps the drill will display the root and the b7 of the dom7 chord and the user has to click on the spot where the 3rd and 5th are located.
4. Another chord drill for the guitar could display the intervals of a chord type and it is the users job to recognize the chord type. A lot of what guitar playing involves is memorization and recognition of chord shapes. If the chord shape is quizzed, as long as the user knows the chord type of the shape displayed and as long as they know where the root of the shap is they will be set for great things.
I can definitely come up with more ideas for drills for the guitar and other aspects of music theory if you feel that these would prove beneficial. I certainly do, as a guitarist and a lover of all forms of music.
Thanks