My 16 years old son and me, we have done a project using Hitechnic Experimenter's kit and 9795 set (Intelligent Building Set). The goal of the project was the automation of a house. My son has used and adapted some circuits he found in the Experimenter's kit handbook.
The construction is the model anyone can find in the set instruction's book but he has added to the model one temperature sensor, one magnetic sensor, one LDR and some LEDs. The circuit is built in a solderless breadboard, is a fast way to build it, and easier than start learning soldering.
The model has the following features: The ventilator start running when the temperature go down; the ligths turn on when the light sensor detects the lightness go down; if the sound sensor that is inside the house detects the noise go up the sistem activates the alarm (lights and siren); the door can be opened with a magnet and the system opens the garaje door when it detects a car.
I've used RobotC for the program, is a program with several tasks, and we had some problems with NXT-G 1.1. The program is in my website http://lrobotikas.net and the translation into English here (http://translate.google.es/