Original Link: http://entan.gl/
This is a great improv app I found on Reddit ages ago and finally got to put into practice when training with the Full Disclosure cast a few weeks back. Add a minimum and maximum amount of time in seconds, and click start. The timer counts down to a randomly set time, blaring an air horn to mark the end of the scene. Then it starts again with a different amount of time. Really awesome, especially when running a min of 2 seconds and a max of 12 seconds to encourage people to get out there and start doing stuff.