Tom rescues Bella at the Ministry in OotP and gets very upset when Molly kills her in DH. Yet JKR claims Tom never knew love and could not love another. Resolve this inconsistency -- show how JKR's claim can be in accord with canon events. (Can be gen -- not necessarily Tom/Bella.)
Draco used the Cruciatus on Thorfin in DH. Tell what happened after that scene. (Can include before and during. Can be gen.)
The Death Eater Light Opera Company Presents an Evening of Gilbert and Sullivan. (Voldemort MUST be in one of the major roles. Fenrir too.)
Walburga Black as Lehar's Merry Widow.
Voldemort is a secret fan of Monty Python -- and the Death Eaters know this. (Several of them are as well.) Do they dare tease the Dark Lord by singing the Spam Song at meetings? Will doing the Dead Parrot sketch earn them a Cruciatus?
All the above prompts can easily be gen -- or not. :)