Couple more:
- allow people to play as a 'guest'. Think you'll get a lot more people trying it out this way
- 910px wide makes it quite hard to fit in many flash portals (seen it come up in the mochi ads distribution area), mine included. I'd love to feature it - any way it can work at 800px wide?
- second the late game stuff; even harder tier 4 decks with exclusive cards to win would be good