I recently participated in the Theros Game Day yesterday. I brought a Rakdos Aggro deck, and I ran into some really tough match-ups. I ended the day 2-2 with the 8th place spot and picked up the promo Nighthowler:
Pretty cool huh? I was actually considering a Golgari Aggro deck, using a few of these bad boys.
I have also been considering Legacy as a potential format. I have been looking at some Legacy Burn decks to try out. These decks are pretty cheap and they look really fun. I'd be ok with running them, even if I didn't win consistently at all. I'd just like to have something to throw down with. My Modern deck is in the works very slowly, but it would be a matter of ordering some cheap cards.
Random note: Arkham Games tourney in early December.