Over at Eindhoven University of Technology, students of the Master course, LEGO Beyond Toys, came up with various amazing third party products that greatly increases the capabilities of the NXT.
Water Pump
GPS Sensor
Wireless Sensor Bridge
Optical Mouse Sensor
Magnetic Grabber
Check out the details @ http://www.bartneck.de/2009/02/16/results-lego-beyond-toys-2/
