Here's a fun thing that I throw into all of my spin classes:
Mid-way through class I play a TV Show theme song (most of which are around 1 minute long), to HOVER to. I let participants determine the level of tension and speed & most challenge themselves well. It's fun for people to hear the old tunes, and a fair amount of time for such an intense move.
See "Televisions' Greatest Hits" CD for song ideas...