D Minor: Possibly The Most Nefarious Key In Western Music
Between scales, drills, sight-reading and recitation of a few standards, I've also spent some time improvising on my brand-new piano, and I've determined that if you want to convey that you or someone else is up to no good, you can't go wrong with d minor.
Witness:
This lovely Beethoven symphony
Toccata and fugue in d minor by J.S. Bach
This piano concerto by Mozart
This symphony by Shostakovich
This violin concerto by Sibelius
Notable exceptions:
Grieg's "In The Hall Of The Mountain King"
"Imperial March" from Star Wars