I practiced harmonics with three web-based tools. The tools overall did tech harmonics. Here is a brief review..
I was excited about this tool, but found it counter intuitive for a new musician. You really have to know your musical notes to use it. I did find the record function to be useful.
This tool allows one to experiment with Arpeggios from different chord progressions. Nice interface and cool auditory experience.
I found this tool to be the most useful. In some cases, such as in the 'Major Chords' section, a sound sample, by way of a video of Bob Marley's 'Get Up, Stand Up' was quite useful in really puiting that chord progression into context.