There is something like this on City of Arabel. The most useful one is "Celestial Concerto" which causes all party members to regenerate hit points for the duration of the bard's song, but the bard cannot use any other songs while the healing song is in effect. The way it works there, you activate the sheet music's special property and your bard song will have the healing effect instead of it's normal effect every time you use it, until you activate the sheet music again to toggle it "off" or until you activate a different sheet music instead (there is also a mass expeditious retreat effect sheet music).
The way the healing one works over there is that your song, once the sheet music is activated, causes all characters in your party and within the normal range of bard song to regenerate a number of hit points per round equal to your heal skill divided by 5, but not more than you have levels of bard, and lasts for the normal duration of your song (I believe it's 10 normally and 15 if you have Lingering Song feat). SO, a level 7 bard with 10 wisdom and lingering song feat can cause all party members to regenerate 2 hit points per round for 15 rounds. A level 10 bard with 8 wisdom and Skill Focus: Healing feat can cause party members to regenerate 3 points per round.
Needless to say, on CoA, bards are the ultimate support character, but personally I think their implementation is too powerful, given how easy it is to find things that add to heal skill and taking the skill focus feat (especially since we get so many feats here). I would like to see something like this here, but perhaps just make it regenerate a number of hit points per round equal to bard level divided by 3, and also make it impossible to use the standard song at the same time.
Frankly, bards here get a bit screwed. I've seen tons and tons of items that give wizards and sorcerers extra spell slots, but never seen a single item that give bards any extra spell slots (and we get fewer spells per rest cycle than they do). Also, according to the PHB, bards are supposed to ignore arcane casting failure due to armour when wearing light armour, and that's something that other servers have implemented, but not here. Before level 11, bard song is really not terribly useful. This would give multi-class bards some usefulness.
Also, a sheet music that has limited charges makes no IC sense whatever. Once a bard knows a song, he/she simply knows it. Besides, I'm really not fond of the endless search in dungeons for consumables that need to be replaced. It merely turns into an endless cycle of dungeon crawling to replace your Candles of Shielding so that you can go dungeon crawling to replace your Candles of Shielding so you can go dungeon crawling to replace your Candles of.....