First of all, thank you for what looks to become a great site and forum for us Hearthstone fans. It is easy to tell that you guys are working hard and have a clear vision of where the site is going.
You've probably already got it in the pipeline, but a thing I'm missing is a 'Notification Bar' or something similar, where reactions to your decks/threads are displayed - the good ol' 'Bell Icon'.
I think a search function would greatly improve the Deckbuilder. For instance, if I were to make a dragon deck, I would search for 'Dragon' to quickly filter what cards synergize with dragons, and not only get cards of the dragon tribe, but also cards with 'Dragon' in their text, e.g. Firetree Witchdoctor.