In addition to Divine Spirit there is also Prayer of Spirit, which will grant an identical buff to an entire party. This spell was originally learned from a book that dropped randomly from instances, but is now trainable from the priest trainer. In addition to an increased mana cost, Prayer of Spirit requires the reagent Sacred Candle.
Cataclysm[]
This section concerns content exclusive to Cataclysm.
With Cataclysm, Divine Spirit and [Prayer of Spirit] will be removed from the game. As Spirit will be the primary mana-regeneration stat, Blizzard doesn't want it to vary as much between solo, small group, and raid play. [Blessing of Kings] and [Mark of the Wild] will not boost Spirit either.[1]