OK, so what exactly does that little "Battle song" icon supposed to do. I couldn't look it up in the manual because the manual I got with the game is all in French. When I use it with Garrick (utterly useless NPC) there is no visible effect.

Thanks! for agreeing that Garrick is utterly useless.

Ok, that's actually Bard Song you're talking about.
What it does:
-increases the party morale and luck
Meaning that luck decreases attack rolls and damage caused by enemies.

Bard are extremely cool. And since Garrick is the only bard in BG he is cool. A character than can cast spells, had some theiving skills and can use any weapon. How can the be utterly useless?

bards rock, especially in IWD. there are plenty of items only a bard can use. there were not enough of these in BG... hopefully this will change in BG2.

Don't forget Eldoth!!!!! Bards are horrible!!! They have one low thief skill, minor magic and are bad fighters, In my opinion your going to far if you say they're average in everything, they're below average in everything!!!!!

Yer know, I can't for the life of me see how singing in the middle of a combat situation can increase morale.