Firstly, the Harmony spell was updated to become Inspirational Boost, so it more or less doesn't stack with it, nor does it effectively exist unless you're not using spell compendium for some reason.
Secondly, Warrior Skald in Races of Faerun is a good way of getting bardic music without levels in bard. In fact it's so badly worded it's probably better than bard levels for getting bardic music, since it lets you get Inspire Greatness like a trillion levels earlier.