Just like any other class the Shaman received several new spells with Wrath of the Lich King. Two new spells that are learned at the trainer and several new spells that are learned with talents.
First of all there is the new Lava burst, learned at level 75. This powerful new offensive spell has a very special effect: as long as Flame shock is on the target it will always be a critical strike. This makes the spell very interesting to Elemental Shamans, as some of their talents are triggered by critical hits. Apart from that this spell does respectable damage. At level 80 a Shaman is able to learn Hex. This spell is similar to the Mage's Polymorph spell, with the target being turned into a frog instead of a sheep ( or cat, pig, penguin or rabbit). In contrast to the sheep the little frog is more resistant to damage and the effect won't break that easily, while the Polymorph effect is canceled with the first point of damage. The downside is that this spell has a 45 second cooldown while only having a 30 second duration, making it only useable once in an encounter.

The different talent trees got some new spells as well. The Elemental Shaman is able to call a Thunderstorm, a short range aoe attack that knocks enemies back and restores some mana to the Shaman. Enhancement Shamans are able to summon Spirit Wolves that fight at his side and restore health to the Shaman whenever they hit. A Restoration Shaman gets the new Riptide spell, a HoT spell with a large initial heal.
Any spell with a cleansing effect was combined in a new talented spell that is able to remove curses as well as poisons and diseases. A new self only buff gives the Restoration Shaman additional critical spell strike chance for his healing spells.