Some interactive art projects from around the world related to play and balls: Research for The Ball Room

POD (by UK artists Alison Ballard and Mike Blow) is an interactive sound installation that allows viewers to experience the physical life of sound waves through the skins of two, six-foot-tall inflatable spheres.

The RedBall Project by Kurt Perschke

Red Paper Heart art studio filled a full sized swimming pool with 65000 ping pong balls.

"It is a child's playground, constructed for adults. This weekend Tate Modern is recreating its 1971 installation Bodyspacemotionthings, which was shut after four days because, newspapers reported, visitors "went bloody mad" and began "jumping and screaming" around the exhibit." (Article in London Evening Standard)

teamLAB, Interactive Installation, Large balls that change color and sound with touch. Contemporary Art at Hong Kong Arts Centre.