Bards are hugely useful in an adventuring party. 7th level is when they really spike up in the power level. At 7th level, bards can start their performances as move actions. Which means in round one of combat, the bard can as a move action do inspire courage and as a standard action cast Good Hope (a 3rd level Bard Spell). This turn gives the party: +2 competence bonus to damage and attacks, +2 morale bonus to attack rolls, damage rolls, and saves. All those bonuses stack! By just one action turn, everyone in the party is getting +4 to hit, +4 damage and +2 on saves.
Plus, the Bard can stop his/her performance as an immediate action to cast Saving Finale to grant a party member a re-roll on a failed save.
Bards are awesome support characters.