Ear training software
GNU Solfege is an ear training program for X Window written in Python, using the GTK+ 2.0 libraries. You can practice harmonic and melodic intervals, chords, scales and rhythms, and you can add new exercises using a simple plain text file format.
Ear training is a big subject with many connections to music theory and performance of music, so I won't even try to make "a complete computer-based ear training course". But I hope someone find this software useful.