I've been enjoying midrange shaman a lot recently, and I've hit rank 5 with this deck(S29).
EDIT: I've hit rank 5 using this deck in both S29 and S30.
Basically, this deck is your standard midrange shaman, with the addition of some extra early-game cards.
Generally, this deck looks to have a strong early game with Argent Squire, Tunnel Trogg, Totem Golem and Spirit Claws. The midgame should be locked down by Flamewreathed Faceless and cards like Azure Drake, while Thing From Below and Thunder Bluff Valiant are used to close out the lategame.
Mulligan hard for your earlygame. Keep your 1-2 drops, and dump everything else; only keep Feral Spirits in aggro matchups.
TLDR, midrange-aggro hybrid shaman. Very reliable deck; it got me to rank 5 on a winstreak in both S29 and S30.
EDIT: I'm still playtesting this deck in S31, especially after the nerfs to Tuskarr and Rockbiter. I'll continue updating this guide, and feedback is appreciated.