I just got back from the FlashForum Konferenz in Dusseldorf, Germany, which was really a greate conference. While there I picked up a copy of MX Magazine, and was really impressed with the quality and quantity of articles (especially on Flash).
If you are in Europe, and you can read German (or at least fake it), I strongly suggest checking this magazine out. It is one of the best magazines (if not the best) I have seen that covers Flash topics.
You can find more info here (in German).