Do some damage: DPS is not a dirty word, even for those who have had some issues with the pewpew lust. Many raid encounters are DPS races and when a 10-man raid is rolling with three healers you are sacrificing a DPS for the safety of healing. Some times it will be need, if not required, for you as a healer to push out some damage when you can to beat that enrage timer. As a resto shaman here are the following recommendations for adding what DPS you can to your raid.
Lighting Bolt Spam – Just like your elemental brothers, start going all emperor and toss out some bolts Shatner style.
Flame shock/Lava Burts – The DoT of Flame Shock and the slow cool down of lava burst allow you to do some damage while still having times to keep an eye on health bars.
Fire Totems – Searing totem for single target DPS and Fire Nova and Magma totems for AoE DPS.
Now, you are not going to be going all out and topping the DPS charts, but if healing is hand and your mana is manageable make sure to help out when you can.