Cross rhythms such as 5 against 4 or 7 against 8 are common.
Non-traditional scales
Irregular time signatures
Cloudbursts by Eric Whitacre
Using one key for the right hand, another key for the left hand.
Putting objects in the piano to create new sounds on the strings or using the piano for knocking or tapping as part of the music.
John Cage Dice Random notes
Blues scales or modes
Chance Music
Bitonality
5/4 or 7/8
Cluster chords
Polyrhythms
Prepared piano
