What music do you use to assess your system?

I'm looking for music that will reveal shortcomings or strengths within ones system. Lets list some of our favorite songs that have: good, fluctuating bass lines, songs that have a solid, centerd vocal, songs that are super complex with alot going on, songs that test tone, songs that test inner and micro detail, songs that test how well a speaker can convey dynamic swing, and any other aspects I didn't mention.

Of course I'm not looking for one song that covers all areas, I'm fine with one song only covering one aspect.

When listing songs, please include what we are looking for in that particular song!