Hearthpwn

Tempo Mage/Secret Mage has been one of my favorites since the days of Flamewaker. Not always the strongest deck, but you have such a variety of tools (good early minions, strong mana-cheating minions, card draw, discovery, freeze, heavy burn spells, counterspells) that you rarely feel totally outplayed. You also have a good variety of tech, should you need it (AoE, immunity). And it's almost exclusively class cards, which is also cool, in my opinion.

My current list runs 28 Mage cards and 2 neutrals. Too many times the Apprentices have only become mid-game cannon fodder, so I exchanged them for new "zero mana 5/5". I see lots of people cutting AI when adding Aluneth, but my experience is that the only thing stopping this deck, is running out of cards to play, so card draw is top priority.