About four months ago, Sully of A Pack Of Gnolls posted this sample DnD spell card. I thought, and still think, that cards for magic spells is a great idea.
Fast forward to June 2011, and the beta release of Dungeon Crawl Classics RPG. The magic system in DCC RPG just begs for a spell card system, with the name, an illustration and effects of each spell printed on the front of a card. The spell card can be flipped face-down when the magic user fails her casting roll, signifying that the spell is no longer available.
My suggestion to Goodman Games is that they reduce and tighten up the range of spell effects so that each spell description and effects can be printed on the front of the card.
Perhaps the initial offering of magic cards can be for first to third level spells, and the range of results be limited to results between 12 and 25 (since a roll of one to eleven means failure, we don't need that range printed on each of the cards).