This is an excellent example of how quickly technology changes. The flip camera is dead after 4 years. The reason...the power of smart phones for video recording. Just one more reason to allow students to use smart phones for learning.
There is a list of tools that you can make for various uses. A moisture sensor for plant soil, a power usage monitor, a laser trip wire, a home weather station, UAV spy plane, wildlife camera, etc. Great for science classes.