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.
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.