1. Which side is truly evil... A contest of two conspiracies. I do like the idea of neither side being evil or good, but both being so corrupted by the need to win that they'll do anything. The Death Eaters think (or maybe they are) protecting the very essence of magic from the corruption of mudbloods, and the Order thinks that they are (well, what's in the book really, but Dumbledore's been pulling the wool over everyone's eyes all along). How will everyone react when this all comes to light?
Okay, so this could be a lovely Malfoy-centric fic, or not. But it's a bunny I'd love to see someone write.
2. Malfoy Manor is like the house from Red Rose, huge and very easy to get lost in (and may eat people). What secrets of their ancestry will (Malfoy of choice) discover when he/she sets out to map the house? Extra points for ghosts and unusual rooms.