[solarmist]

This is a first step toward writing your own ear training software, like EarMaster Pro. It has chord training, interval training, etc. This is probably closest to melodic sight-"singing" (you can use a midi instrument too) which is randomly generated melodic sequences, although it's aimed at singers so no chords.

There's also sightreadingfactory which generates random music to play as well. This one allows you to pick an instrument, level, time signature, and key. But it isn't interactive. It'd be great if they added web midi.