jeppe hein is excellent. In the Line of Fire is a nice profile article @ freize.com. kopenhagen.dk has an interview. or go to nicolai wallner for many images but no text.

• Let Me Show You the World (2000), a tiny hole in a wall which emits a soft breeze (to flutters your eyelashes) when you peer inside
  
• Continuity Inbetween (2002), an unbroken jet stream of water leaps between two walls
  
• 360 Presence (2002), a large steel sphere sits in the gallery space until a visitor enters the room. at which point it starts rolling around uncontrollably, bashing into walls, visitors, etc.
  
• Space in Action / Action in Space (2002), a fountain consisting of vertical walls of water. sections of the fountain shut off when you approach, allowing you to enter the fountain's space and stand surrounded by water inside
  
• Bear the Consequenses (2003), a flame bursts out of a wall when someone enters the gallery. the flame's size and intensity vary as visitor's appoach closer
  
• Changing Space (2003), over twenty-five minutes, a gallery wall slowly moves five metres, from the middle of the room toward the end wall, until the room is only a half metre wide.